Set Up TrekMail in Mozilla Thunderbird

Thunderbird can often find a mailbox automatically. If its first guess is wrong, use manual configuration and copy the settings TrekMail shows for that mailbox.

Before you start

Open Mailboxes, choose the mailbox, then open Apps & devices. Keep that screen nearby. It is the source of truth for the incoming and outgoing server names, including a verified branded hostname supplied by a White Label provider.

You also need:

• The full mailbox address, such as you@example.com.
• An app password, or the mailbox password if the mailbox still accepts it. Do not use the TrekMail dashboard password.
• A sending-ready status. Thunderbird tests incoming and outgoing mail together.

Apps & devices shows the sign-in mode: App passwords only requires an app password; Mailbox password or app passwords accepts either. Create one in webmail under Settings > App passwords, or in the dashboard under Mailboxes > the mailbox > Security > App passwords. See Mail app passwords.

Add the account

1. Open Thunderbird's menu and choose New → Existing Mail Account. You can also open Settings → Account Settings → Account Actions → Add Mail Account.
2. Enter your name, full mailbox address, and the password prepared above.
3. Let Thunderbird try automatic setup. Continue only if the server names and security settings match Apps & devices and there is no certificate warning.
4. Otherwise, select Configure manually.

Enter the incoming settings

• Protocol: IMAP
• Server: copy the incoming server from Apps & devices
• Port: 993
• Connection security: SSL/TLS
• Authentication method: Normal password
• Username: the full mailbox address

Enter the outgoing settings

• Server: copy the outgoing server from Apps & devices
• Port: 465 with SSL/TLS
• Authentication method: Normal password
• Username: the full mailbox address

Port 587 with STARTTLS is the supported alternative when a network blocks port 465. Do not pair port 587 with plain or implicit SSL.

Select Re-test. When both checks pass without a certificate warning, select Done and allow the first folder sync to finish.

For a standard TrekMail mailbox, the usual hosts are imap.trekmail.net and smtp.trekmail.net. A verified White Label setup can show branded hosts instead. Use the values on the mailbox screen rather than replacing them with a server name guessed from the email address.

If Thunderbird will not connect

• Authentication failed: re-enter the full address as both usernames and check the sign-in mode in Apps & devices. If you see "Sign-in failed. This mailbox accepts app passwords only: create one in webmail under Settings > App passwords.", create one there and enter it in Thunderbird. A generic password error can have the same cause.
• Receiving works but sending fails: confirm that SMTP authentication is enabled. Try port 587 with STARTTLS if the network blocks port 465.
• Certificate warning: stop and copy the server name again from Apps & devices. Do not accept a certificate for a different hostname.
• Old password keeps returning: remove only the saved password for the displayed IMAP or SMTP host from Settings → Privacy & Security → Saved Passwords, then retry with a valid password. If an app password was replaced or revoked, create or use its replacement.
• Too many connections: close unused clients or reduce the number of folders Thunderbird checks for new mail. See the connection limits in the article below.

If it still fails, open a support ticket with the exact Thunderbird version, server name, port, security mode, and error message. Do not include the mailbox password or an app password.