Mailcow 2-factor auth with Thunderbird app password

Timosesu

Hi,

I tried setting 2-factor auth in Mailcow (not SOGO) and use Thunderbird via IMAP.

However, setting an app password in Thunderbird does not seem to work. The IMAP can not be synced.

Is there any way to use 2-factor auth and still use Thunderbird?

esackbauer

You must be doing something wrong. I use 2FA and app passwords with Thunderbird without problem. Which mailcow version you are on?
Did you check the dovecot logs?

Timosesu

The dovecot log keeps saying the following 3 times:

auth-worker(2348520): conn unix:auth-worker (pid=132,uid=401): auth-worker<315>: lua(user@mydomain.net,192.168.3.59,<[REDACTED]>): Password mismatch (SHA1 of given password: [REDACTED])

Then ends with

imap-login: Disconnected: Connection closed (auth failed, 3 attempts in 7 secs): user=<user@mydomain.net>, method=PLAIN, rip=192.168.3.59, lip=172.22.1.250, TLS, TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)

The App password is set under Thunderbird Settings -> Privacy & Security -> Passwords -> “Use primary password”

As soon as I deactivate TOTP again in Cow profile I am able to connect again via Thunderbird IMAP.

esackbauer

Have you used the generated password from mailcow? This is what I do. And of couse the app password must be different from your login password.
Which mailcow version are you on?

[unknown] Thunderbird Settings -> Privacy & Security -> Passwords -> “Use primary password”

That is the wrong location. you have to do it under the account settings where you configure IMAP and SMTP.

Timosesu

esackbauer

What is “the generated password from mailcow”?

What I have is:

Mailcow account mail
Mailcow account password
Mailcow provided TOTP authentication (I can generate TOTP tokens)
A Thunderbird App password

In Thunderbirda I use the Mailcow account mail and password to login via IMAP.
I have set up Thunderbird App password.

I now tried using another password than the one for Mailcow in Thunderbird for the app password. Still, it does not work.

[unknown] Thunderbird Settings -> Privacy & Security -> Passwords -> “Use primary password”

That is the wrong location. you have to do it under the account settings where you configure IMAP and SMTP.

I don’t know where under IMAP/SMTP I would be able to set a Thunderbird app password. I can only set my Mailcow password type under Account Settings for the mailcow mail account.

Mailcow version is: 2025-10a

esackbauer

Timosesu A Thunderbird App password

where do you have this from?
App passwords are generated from the user login page to mailcow, and then select tab “app passwords”. This is where you also can have them generated. Make sure that IMAP and SMTP is allowed for the app password.

Timosesu In Thunderbirda I use the Mailcow account mail and password to login via IMAP.

That contradicts what you are doing. To login via IMAP, use the Mailcow email address of that account and the app password, not your regular account password!

Timosesu

Wow, thank you esackbauer. This was quite the misunderstanding.

My previous understanding was that by app password it is meant that one has to configure a password for Thunderbird itself (as in a “password for the app”).

Now I understood that Mailcow offers a way to configure further passwords unlocking specific protocols for specific app usage purposes. Probably to protect the “root”/“user” password.

Thanks again!