IMAP authentification & dovecot-2.3


I use nextcloud server (13.0.2) with IMAP authentification since a while successfully (dovecot-2.2 as imap server).
Since I upgrade from dovecot-2.2 to dovecot-2.3, I have issue only with nextcloud (no issue with others imap client) :

  1. I login on webui successfully,
  2. I use webui without issue,
  3. Suddenly I’m disconnected. It can happen a few minutes later or hours (random).

On dovecot side, I have this log when disconnection happens :
May 23 16:41:13 server dovecot: imap(user@domain.tld)<16838><2v07g+BsJrs+0n0I>: Connection closed (No commands sent)

On nextcloud side, I have this log :
Warning core Login failed: ‘user@domain.tld’ (Remote IP: ‘xxxxxxxx’) 2018-05-23T16:41:13+0200

First of all, I discuss with dovecot guys but they don’t modifying anything about that since 2.2 to 2.3. Then I understand I have this issue only with nextcloud. So maybe it’s a nextcloud issue ?

PS: I talked about the webui, but I have exactly the same issue with nextcloud-client (2.3.3).

Hope you can help me. Thanks.

Open an issue on, the developers can perhaps give you more specific pointers where and what to log.

I’m not sure how this is handled in detail, I thought it just verifies the credentials with the imap server and the session is handled by Nextcloud (no parallel session is opened via IMAP). Is the disconnection time related to the log on dovecot server that the connection was closed?

Thanks for your answer. I’ll open an issue soon.
Yes (for the disconnection time).

It seems to be an SSL issue because I also have a SSL alert from dovecot, I’ll try without SSL later.


Finally I found a solution : my imap and nextcloud server are on the same host, so I disable SSL for imap authentification when connection are from localhost and it works.

Have a nice day!

I have the exact same problem. Did you ever get a proper solution (other than disabling ssl)? Could you post a link to the issue page you opened on github?
I have no ssl warning in dovecot.
Also, if I have the “No command sent”, that still means it passed the authentication phase.


I didn’t open issue on github and, because I don’t need ssl, I didn’t find a way to use ssl without issue.
Sorry for the non help. :confused: