Nanoman's Company Support

These pages are intended to be referenced by customers of Nanoman's Company. Visitors are welcome to reference these pages, but our support for you may be limited.


Mozilla Thunderbird

Mozilla Thunderbird is an excellent email client that can be downloaded for free from its website:

Unfortunately, we and most of our customers dislike several of the default settings in Thunderbird. Fortunately, all these settings can be changed relatively easily.

This page contains procedures for changing Thunderbird's default configuration, and it also includes our rationale for making these changes. You may ignore our "Rationale" lines if these don't interest you, but please read every step when following these instructions, and please contact us if you find any problems.

The information on this page was written for configuring Mozilla Thunderbird version 91.4.1 as it would normally be configured by Nanoman's Company. Most of this will probably continue to apply for later versions, but your results may vary.

With the release of each new version of Thunderbird, we consider revising this page, but we don't always do so. We review this page before each large deployment, and/or when we notice problems or significant changes in Thunderbird, but we're currently unable to justify more frequent reviews/revisions.

Connection Information

Before using Thunderbird or almost any email client, you'll need to know your email address, and you'll also need to know your connection information for your incoming and outgoing email servers. You use your incoming server to receive messages, and you use your outgoing server to send messages, so if you have a problem with either of these tasks, then there might be something wrong with the connection information you entered when configuring your email client.

Here's an example of what the connection information might look like for someone with the email address alice@example.tld:

DetailIncoming ServerOutgoing Server
SecurityTLS (or "SSL/TLS")TLS (or "SSL/TLS")
AuthenticationSASL (or "Normal Password")SASL (or "Normal Password")

Every email provider is unique, and your connection information for your email address might be quite different from this example. If you don't know these details for your email address, then please contact your email provider.

Additionally, you should ask your IT provider if local caching of your email account's messages should be enabled on your computer. This is the default setting in Thunderbird and most other email clients, and it's intended to help improve performance while working around potential connectivity problems. Most users will want this enabled, but it can cause problems for a minority of accounts/computers/networks/organizations/users. We haven't written a guide that describes the variables to consider when making this decision, but if you're a customer of ours who needs to know what would work best for you, then you're welcome to contact us for personalized advice.

Thunderbird Installation

The procedure for installing software on a computer can vary drastically from one computer to another. Many thousands of different computer configurations have been deployed by our company and others, so we're not going to attempt to describe how to install Thunderbird on any computer. If you don't know how to install software on your computer, then please contact your IT provider.

Nanoman's Company has installed Mozilla Thunderbird on every PC that we've deployed since Thunderbird's early versions were released in 2003. If your PC's current operating system was installed by us from 2003 to present, then unless somebody has removed it, you should already have Thunderbird installed.

Thunderbird Preferences

After Thunderbird is installed, we recommend changing several settings before configuring it to access your email account. To change these settings, please follow these steps:

  1. Open Mozilla Thunderbird.
  2. If the "Set Up Your Existing Email Address" tab appears, close it.

    Rationale: By default, instead of using the generally much more efficient maildir format for local message storage, Thunderbird uses the mbox format. After you configure an email account in Thunderbird, you can't change the format it uses for storing local copies of the account's messages without removing and reconfiguring the account. To avoid this extra work, don't configure your account until after you finish adjusting Thunderbird's "Preferences". Mozilla officially recommends that Thunderbird users use mbox due to problems with Mozilla's maildir implementation, but none of these problems have affected our customers, and we consider the benefits of maildir to significantly outweigh these risks.

  3. Close the "Thunderbird Privacy Notice" tab.
  4. Assuming you're not using Apple macOS, press Alt+V on your keyboard to open the "View" menu, and then select "Toolbars" -> "Menu Bar" to enable the menu bar.

    Rationale: It's very easy to ask a customer to access something from a menu that has a word for a name, whereas it's very tedious -- and sometimes frustrating for them -- to ask them to find Thunderbird's menu button and then navigate its submenus. Our customers consistently complain when they can't find the menu bar to access a function that's accessible through it, whereas we've never heard a customer say that they don't want to see Thunderbird's menu bar. Hiding the menu bar makes sense on devices with small screen sizes like smartphones, but it makes less sense on a typical modern PC screen.

  5. Open the "Preferences" tab. Where you find this depends on your operating system:
    Operating SystemLocation
    Apple macOS"Thunderbird" menu -> "Preferences"
    Microsoft Windows"Tools" menu -> "Options"
    UNIX (FreeBSD, GhostBSD, OpenBSD, Xubuntu, et cetera)"Edit" menu -> "Preferences"
  6. If you don't see the tab names beside the "General", "Composition", and other icons on the left side of the "Preferences" tab, then maximize the Thunderbird window.

    Rationale: Thunderbird hides these tab names if the Thunderbird window is too narrow to fit both the tabs' icons and names beside each other. You can hover your mouse cursor over the icons to see their names temporarily, but we find it easier to guide people through these instructions when the tab names are displayed constantly.

  7. On the "General" tab, uncheck the checkbox beside "When Thunderbird launches, show the Start Page in the message area".

    Rationale: No customer has ever told us that they want to see something other than their email messages when they open Thunderbird, but we've heard many customers complain when they saw a web page instead.

  8. On the "General" tab, scroll down to the "Language & Appearance" section, and under "Language", if you see "English (United States)", click this to select "Search for more languages". Click "Select a language to add", select "English (Canada)", click the "Add" button, click the "OK" button, and then click the "Apply and Restart" button, which should cause Thunderbird to close and open again. When Thunderbird opens again, close the "Account Setup" tab if it opens, and you should be returned to the "Preferences" tab.

    Rationale: Most of our customers use Canadian English primarily.

  9. On the "General" tab, scroll down to the "Reading & Display" section, and under "Open messages in", put a check in the radio checkbox beside "A new message window".

    Rationale: This is the preference of the vast majority of our customers, but it's not the only reason why we change this setting. A good default setting in Thunderbird is that it will reopen tabs that were open when Thunderbird was closed, but we've encountered several situations where customers have unwittingly had hundreds of messages open in tabs, and this has resulted in drastic performance loss. For the minority of customers who prefer opening messages in tabs, restoring this default setting is relatively easy.

  10. On the "General" tab, scroll down to the "Network & Disk Space" section, and under "Indexing", change "Message Store Type for new accounts" from "File per folder (mbox)" to "File per message (maildir)".

    Rationale: This eliminates the need to routinely use the "Compact Folders" function, and it eliminates many related problems. This needs to be set before you configure your account settings because Thunderbird can't change the storage type for an account's local messages after the account has been configured. Please don't skip this step.

  11. On the "Composition" tab, under "Spelling", put a check in the checkbox beside "Check spelling before sending".

    Rationale: We've had a few customers tell us that they want their messages sent without having their spelling checked beforehand, but many of our customers have told us that they really like this feature, so we enable this by default.

  12. On the "Composition" tab, under "Spelling", change "Language" from "English (United States)" to "English (Canada)". Depending on your operating system, you might have to click the "Download More Dictionaries" link to download and add this dictionary, and you might need to close Thunderbird and open it again before this will appear under "Preferences". If the "Account Settings" screen reappears, close it, and then open the "Preferences" tab again.

    Rationale: Most of our customers use Canadian English primarily.

  13. On the "Composition" tab, scroll down to the "Attachments" section, and uncheck the checkbox beside "Offer to share for files larger than".

    Rationale: Most of our customers don't trust "clouds", and we don't either.

  14. On the "Privacy & Security" tab, under "Passwords", consider putting a check in the checkbox beside "Use a Primary Password". If you decide to do this, then follow the steps on the "Primary Password" screen to create your "Primary Password" for Thunderbird.

    Rationale: By default, anybody who opens Thunderbird on your computer would be able to send and/or receive messages as if they were you (assuming your email account had been configured), but this setting would ask for your Thunderbird "Primary Password" to be entered every time Thunderbird is opened. If a typical user got access to your computer with Thunderbird closed, then this could protect your email, but this probably wouldn't defend your email against a determined attacker, so we advise our customers to contact us if you need better IT security.

  15. On the "Privacy & Security" tab, under "Junk", put a check in the checkbox beside "When I mark messages as junk".

    Rationale: Despite our best efforts, our customers continue to receive varying amounts of email spam, so this makes it easier for them to sort through their messages.

  16. On the "Privacy & Security" tab, scroll down to the "Thunderbird Data Collection and Use" section, and uncheck the checkbox beside "Allow Thunderbird to send technical and interaction data to Mozilla".

    Rationale: We appreciate that Thunderbird's developers want to study how Thunderbird is used so that they can make improvements accordingly, but we don't want to risk the possibility of any customer's private data being released.

  17. On the "Privacy & Security" tab, scroll down to the "Security" section, and under "Antivirus", put a check in the checkbox beside "Allow antivirus clients to quarantine individual incoming messages".

    Rationale: If a customer uses a virus scanner, then this should help it fulfill its purpose.

  18. On the "General" tab, scroll down to the bottom of the tab, and click the "Config Editor" button.
  19. In the "Search" box, type "nglayout.enable_drag_images", and then double-click its Value ("true" by default) until it changes to "false".

    Rationale: This fixes an officially unsolved problem that has affected our customers.

  20. In the "Search" box, delete everything, type "", and then double-click its Value ("true" by default) until it changes to "false".

    Rationale: Our customers who use online messaging systems like IRC and XMPP have told us that they prefer using separate software like HexChat, Psi, and Pidgin, so this reduces clutter in their Thunderbird windows.

  21. Close the "Advanced Preferences" tab.
  22. Close the "Preferences" tab.
  23. In the top-right corner of the Thunderbird window, click the icon with the mouseover text "Switch to the calendar tab".
  24. In the top-right corner of the calendar, click "Month" to switch to month view.

    Rationale: Most of our customers who use Thunderbird's calendar feature prefer this view, and for those who don't, changing it is easy.

  25. Close the "Calendar" tab.

Account Settings

Multiple email addresses can be configured in Thunderbird, and each may optionally have its own separate "Inbox", "Sent", "Trash", and other folders. After configuring Thunderbird's "Preferences", and with your email connection information handy, please follow these steps for each email address that you want to configure in Thunderbird:

  1. Open Mozilla Thunderbird.
  2. Open the "Account Settings" tab. Where you find this depends on your operating system:
    Operating SystemLocation
    Apple macOS"Tools" menu -> "Account Settings"
    Microsoft Windows"Tools" menu -> "Account Settings"
    UNIX (FreeBSD, GhostBSD, OpenBSD, Xubuntu, et cetera)"Edit" menu -> "Account Settings"
  3. In the bottom-left corner of the "Account Settings" tab, click "Account Actions" -> "Add Mail Account".
  4. In the "Your full name" box, type your name or whatever you want to appear in the "From" line of your messages.
  5. In the "Email address" box, type your email address.
  6. In the "Password" box, type the password for your incoming server.
  7. Click the "Configure manually" button.

    Rationale: This screen's "Continue" button causes Thunderbird to spend some time trying to guess the connection information for your email provider, but it doesn't always guess all the details correctly, so we find it's better to manually enter these details.

  8. Edit the incoming and outgoing email server settings to precisely match the details from your email provider.
  9. Click the "Advanced config" link, and then "OK" to confirm that you want to proceed without testing the correctness of the configuration you provided.

    Rationale: Assuming you entered your email connection information correctly, this will spare you from having to open the "Account Settings" tab again.

  10. On the left side of the "Account Settings" tab, select your email address.
  11. If your email address is being used for an organization, then you should type the organization name into the "Organization" box ("Acme Widgets, Incorporated", for example).

    Rationale: This appears as the "Organization" email header, which isn't visible by default in most email clients, but some people may expect and/or require this to be set.

  12. If you have a "signature block" file (not to be confused with an OpenPGP signature file), then put a check in the checkbox beside "Attach the signature from a file instead", and then "Choose" the file. If you don't have a "signature block" file but do have some text that you want added to the bottom of all your email messages, then type it into the "Signature text" box.

    Rationale: For various reasons, many people need or want a "signature block" (also known as an email signature) added automatically to the bottom of every message they write. It's generally recommended that such text be limited to a maximum of four lines, and the inclusion of legal disclaimers is generally considered ineffective for several reasons (example: disclaimers should appear before content is presented, not after). Thunderbird will precede signature blocks with a line containing the signature delimiter string ("-- "), and this can be disabled in Thunderbird's "Config Editor" by changing the Value of "mail.identity.default.suppress_signature_separator" to "true", but we don't recommend doing so because this is intended for better interoperability with email clients that support it.

  13. Under your email address on the left side of the "Account Settings" tab, select "Copies & Folders".
  14. If you want the "Cc" box to be visible by default for every message that you write, then put a check in the checkbox beside "Cc these email addresses".
  15. If you want the "Bcc" box to be visible by default for every message that you write, then put a check in the checkbox beside "Bcc these email addresses".
  16. Under your email address on the left side of the "Account Settings" tab, select "Composition & Addressing".
  17. If you want to send messages in plain text, then uncheck the checkbox beside "Compose messages in HTML format". If not, then leave this checked.

    Rationale: Plain text is what we and some of our customers prefer, but most of our customers prefer the default setting. In the default settings for Thunderbird's "Send Options" (under Thunderbird's "Preferences" tab -> "Composition" tab), Thunderbird will attempt to send both plain text and HTML versions as a multipart message, and this works very well for the vast majority of messages, but at the cost of the message's body requiring about double the storage space and bandwidth.

  18. If you don't want to be a top-poster, then change "start my reply above the quote" to "start my reply below the quote". If you want to be a top-poster, then change "below the quote (recommended)" to "below my reply (above the quote)".

    Rationale: On large mailing lists and among advanced users, using the posting style known as "top-posting" is generally discouraged. Unfortunately, despite our advocacy of superior posting styles, virtually all our customers choose to be top-posters most/all of the time.
    A: Because it complicates the process of reading message thread history.
    Q: Why is top-posting such a bad thing?
    A: Top-posting.
    Q: What is the most annoying thing in newsgroups and in email?

  19. Under your email address on the left side of the "Account Settings" tab, select "Junk Settings".
  20. Put a check in the checkbox beside "Trust junk mail headers set by".

    Rationale: Most of our customers use SpamAssassin on their email servers, and Thunderbird uses SpamAssassin as its default option for this setting, so this helps Thunderbird sort out email spam more efficiently.

  21. Put a check in the checkbox beside "Move new junk messages to".

    Rationale: Virtually all our customers expect email spam to go to their "Junk" folders, not to their Inboxes or elsewhere.

  22. Under your email address on the left side of the "Account Settings" tab, select "Synchronization & Storage".
  23. If you need/want to disable local caching of email messages, then uncheck the checkbox beside "Keep messages in all folders for this account on this computer", and then click the "Save" button to confirm. If you need/want to keep local caching enabled, then leave this checked.

    Rationale: Most of our customers should keep this checked, but some shouldn't, and some should click the "Advanced" button to select only a few folders (Inbox, Drafts, Sent, and/or maybe others). Please contact us if you're a customer of ours who needs to know which option is best for you.

  24. Under your email address on the left side of the "Account Settings" tab, select "End-To-End Encryption".
  25. Under "OpenPGP", click the "Add Key" button.
  26. Follow the steps to either import your existing OpenPGP private key if you have one already, or to create a new key if you don't. If you create a new key, we recommend changing the key type from RSA to Ed25519/Curve25519 ("Elliptic Curve").

    Rationale: RSA has been around longer, but Ed25519/Curve25519 are much more efficient despite their shorter key lengths, and many people believe Ed25519/Curve25519 to be stronger.

  27. Under your email address on the left side of the "Account Settings" tab, on the "End-To-End Encryption" tab, scroll down to the "Default settings for sending messages" section.
  28. Consider putting a check in the radio checkbox beside "Require encryption by default".

    Rationale: If you're certain that all your correspondents use encrypted email, then you should definitely check this, but if not, then it might be unnecessary and/or disruptive to your workflow. Please see our OpenPGP page for more information.

  29. Put a check in the checkbox beside "Add my digital signature by default".

    Rationale: This will attach a small file named "OpenPGP_signature.asc" to every message that you send, and this file can help protect the integrity of your messages. Please see our OpenPGP page for more information.

  30. Uncheck the checkbox beside "Attach my public key when adding an OpenPGP digital signature".

    Rationale: All your messages should be "digitally" (cryptographically) signed using OpenPGP, but we don't know anybody who needs to attach their OpenPGP public key to every message they send.

  31. If you trust your email server, then uncheck the checkbox beside "Store draft messages in encrypted format".

    Rationale: We'd strongly prefer to keep the default setting, but when working with messages that have large attachments on computers that are old and/or have slow connections to their servers, this can severely degrade Thunderbird's performance.

  32. Close the "Account Settings" tab.
  33. Under your email address on the left side of the Thunderbird window, click "Inbox".

    Rationale: This is usually a good test to see if you correctly entered your incoming email server details.

  34. To the right of the column headers "Subject", "Correspondents", "Date", et cetera, there's a little icon that will show "Select columns to display" if you hover your mouse cursor over it. Click this icon to set these columns to display:
    • Thread
    • Starred
    • Attachments
    • Read
    • Correspondents
    • Junk Status
    • Date
    • Size
    • Subject (currently missing from this list, but might be included in later versions)

    Rationale: By default, Thunderbird has "Size" unchecked, but we believe that this should be checked by default because this helps to warn users about large messages. If a user wants to know why some messages take a long time to download and/or display, then this should help them to understand why.

  35. Click and drag the column headers to arrange them in whatever order works best for you. Going from left to right, the vast majority of our customers prefer this sequence:
    1. Thread
    2. Read
    3. Starred
    4. Date
    5. Correspondents
    6. Subject
    7. Size
    8. Attachments
    9. Junk Status
  36. To apply the message column arrangement to all your email folders, click the "Select columns to display" icon, select "Apply columns to" -> "Folder and its children" -> (your email address) -> (your email address), and then click "OK" to confirm.

    Rationale: If you don't do this, then only the folder that you arranged would have this arrangement.

  37. Try writing a test message to your own email address.

    Rationale: This is usually a good test to see if you correctly entered your outgoing email server details.

Thunderbird Add-ons

Mozilla Thunderbird comes with almost all the functionality that our customers require, but it's missing some functionality that's important to some of our customers. Fortunately, Thunderbird has a large selection of add-ons that are able to provide more functionality, including some that our customers consider important:

MoreLayouts: Change the Attachments Pane's Appearance
When composing a message in Thunderbird before version 91.0, any attachments would be listed vertically in a pane to the right of the "To" and "Subject" boxes. Starting with version 91.0, Thunderbird's developers decided to move the attachments pane to the bottom of the message composition window, and to list attachments as horizontal "pills". Many of our customers preferred the old position because it was much more noticeable, and most of our customers who regularly send several attachments per message preferred the old vertical list format because they found it easier to read.
This add-on changes the appearance of the attachments pane to the old position and format that many of our customers prefer. After installing it, go to "Tools" menu -> "Add-ons and Themes", click the "Extensions" tab, click the "Add-on Options" icon beside "MoreLayouts", and in the "Compose" section, change "Attachment list location" from "Bottom" to "Top".
LanguageTool: Grammar Checker
Thunderbird comes with a spelling checker built-in, but it doesn't come with a grammar checker. This add-on provides this functionality.
Please be aware that this add-on submits text from your messages to a remote server for automatic grammar analysis. If you're concerned about the security or privacy implications of this add-on, then you either shouldn't use it, or you should run your own LanguageTool server.
Textmarker: Highlighter
When writing an email message with HTML formatting enabled, some customers sometimes want the ability to add a highlighter effect to a specific section of text. Thunderbird's built-in editor makes it easy to select a specific section of text to assign it a different font size, text colour, boldness, or other effects, and the built-in editor can change the background colour for the whole message, but it lacks the ability to change the background colour for a specific section only.
This add-on provides the highlighter formatting feature that some of our customers want. Thunderbird's developers have received a request to add this feature to their built-in editor, but it's unknown if or when this feature will be added.
Manually sort folders: Customized Sorting of Folder Pane
By default, Thunderbird's folder pane is sorted to have "Inbox" at the top, followed by other standard folders like "Drafts", "Sent", and "Trash", and then all other folders are sorted alphabetically below these. This is what most of our customers want, but some of our customers want the ability to customize how these folders are sorted.
This add-on adds a "Manually sort folders" option to Thunderbird's "Tools" menu that allows you to customize the sorting of your folder pane. If you have multiple email addresses configured in Thunderbird, then this can be used to customize the sorting of these too.
Sieve: Sieve Support
Most of our customers use email servers that support an email filtering language named Sieve. Most of these customers are satisfied with how their email providers configured their email accounts to deliver messages into their Inboxes or Junk folders, but some customers need more control over this configuration.
Thunderbird's developers have received a request for built-in Sieve support, so maybe an add-on won't be needed someday. In the meantime, we've found that this add-on works really well.
LookOut (fix version): TNEF Support
A small minority of email users are using a closed-source email client named Microsoft Outlook that's notorious for being horribly insecure, extremely unreliable, and having severe problems with data corruption. This awful email client has been a terrible burden on the people who are still using and/or supporting it, and because it doesn't adhere to the open standards that all email clients are expected to follow, it also causes problems for the correspondents of its users.
One of the many problems with Microsoft Outlook is its default method of sending attachments. While virtually every other email client released since the year 1992 has used the totally reasonable and globally adopted MIME (Multipurpose Internet Mail Extension) standard for attaching files, this horrid email client from 1997 uses a proprietary format named TNEF. TNEF has zero advantages over MIME, provides zero benefits to senders or recipients, is drastically inferior to MIME, and most email clients don't support it because it's not the Internet standard.
Unfortunately, some of our customers sometimes receive files that have been encapsulated in TNEF format by the wretched Microsoft Outlook email client that some of their correspondents are using by force or by ignorance. Instead of seeing one or more files as standard MIME attachments, they'll see a single attachment named "winmail.dat" or "win.dat". These "winmail.dat" or "win.dat" attachments are TNEF files, and they contain the files sent by the sender.
If you ever receive a TNEF file from one of your correspondents, then we very strongly recommend that you advise them to upgrade to a better email client, or to at least reconfigure their problematic email client to attach files using MIME instead of TNEF. If they ask why, please feel free to refer them to this section of this page. We won't support Microsoft Outlook, so if they don't know how to make this change, then they'll have to either ask their IT provider for assistance, or consider getting a better IT provider.
If somebody who sent you a TNEF file is unable to resend it as a standard MIME attachment, or if you're unable to ask them to do so for some reason, then you might want to install this add-on. This add-on attempts to convert proprietary TNEF attachments into standard MIME attachments.
Thunderbird's developers have received a request to add built-in support for TNEF, but TNEF usage is declining and widely discouraged, so Thunderbird will probably never have built-in support for it. We consider TNEF to be an abomination that nobody should have to support, so we'd rather see Thunderbird's developers focusing on improvements that are actually good for society.

Installing Thunderbird add-ons is pretty straightforward:

  1. Open Mozilla Thunderbird.
  2. Go to "Tools" menu -> "Add-ons and Themes".
  3. In the search box beside "Find more add-ons", enter the add-on's name.
  4. On the search results page, beside the add-on you want to install, click the "Add to Thunderbird" button.
  5. When asked if you want to add the add-on, click the "Add" button.
  6. Click the "OK" button to acknowledge that the add-on has been added to Thunderbird.
  7. On the search results page, if the add-on has the words "requires restart" beside it, close Mozilla Thunderbird, and then open it again.

Missing Features

At the time of this writing, Thunderbird is missing some features that some of our customers want, and these features aren't available through add-ons for Thunderbird's current version:

Option for Autocorrect
Autocorrection is strongly disliked by some people, and strongly desired by others. Some of our customers have told us that they want Thunderbird to have an autocorrect feature, but we know that many of our customers would never want it enabled.
Thunderbird has an add-on named mms Auto Correct that used to provide autocorrect functionality, but this add-on isn't compatible with Thunderbird's current version. We're not aware any other efforts to offer autocorrect for Thunderbird.
Option for Displaying Message Excerpts in Message Listing Pane
Some of our customers want the option to have excerpts from messages displayed in Thunderbird's message listing pane. The idea is that one or more lines of text from the top of each message would appear among this pane's other details ("Date", "Correspondents", "Subject", et cetera), thereby sparing the user from having to open a message to see the text at its top.
Thunderbird's developers are working on an update to add this feature, but it's unknown if or when this feature will be added. We also don't know if their implementation will recognize the first few lines of replies that don't use top-posting.

Nanoman's Company could create new add-ons for Thunderbird that would provide features that our customers have wanted, but we haven't investigated how much effort this would require. If you're a customer of ours who requires any of these features, then you may contact us to offer to fund the creation of such add-ons, but keep in mind that we haven't estimated how much these would cost to make, so these might be expensive endeavours.

Email Risks

Sending an email message is as risky as sending a postcard. Please see our OpenPGP page for information about how you can use Thunderbird to protect the integrity and/or secrecy of your email messages.