Setting up Thunderbird for Android with IMAP and SMTP

Thunderbird for Android is the open-source mail client that was previously called K-9 Mail. It is available from F-Droid and Google Play and supports IMAP and SMTP with manual server settings. This guide covers an ITProMail account on Android using an app password and encrypted connections.

Step 1: Create an app password

In the webmail, open Account, then Security, and create an app password labelled for this phone, such as "Android phone". Store it in a password manager. Revoking this app password later will disconnect only this device.

Step 2: Add the account

Open the app and start adding an account. Enter your full email address and the app password. Because automatic detection may not find custom server settings, choose the manual setup option and select IMAP as the account type.

Step 3: Enter the server settings

If your network blocks port 465, use STARTTLS on port 587 for the outgoing server instead. Keep TLS enabled in both cases.

Step 4: Choose sync and folder options

Once the account is created, the app will list your folders. Check that the folder for sent mail and the folder for drafts match the names used in the webmail. If you keep many folders, enable only the ones you need for push or frequent polling, because each folder you poll adds to battery use.

Battery behaviour depends on the phone and on Android's background restrictions. If new mail arrives late, check the app's battery settings and allow it to run in the background.

Step 5: Test it

Send a message to an address you control, and check that it appears in the webmail Sent folder. Then send a message from the webmail to the phone and confirm that it arrives. These two checks confirm that both the outgoing and incoming connections work.

Notes on security

The app stores your account credentials on the device, so use a screen lock and keep the phone's operating system updated. If the phone is lost, revoke the app password for that device from Account, then Security. Your other devices will keep working.

Do not enable any option that accepts untrusted certificates. If the app reports a certificate problem, check the server name against imap.itpromail.com or smtp.itpromail.com before doing anything else.

If something fails

Login failures are almost always caused by using the account password instead of the app password, or by a username that is not the full address. Connection failures usually come from a wrong port or a security setting that does not match the table above. For the IMAP and SMTP reference, see IMAP and SMTP settings.