unsupported auth mechanism

Josef 'Jeff' Sipek jeff.sipek at open-xchange.com
Mon Aug 24 19:37:49 EEST 2020

On Mon, Aug 24, 2020 at 17:11:04 +0200, absolutely_free at libero.it wrote:
> Hi,
> last friday I upgraded from dovecot- to dovecot- (FreeBSD).
> Since then, I started having some issues with some customers.
> The log I see is like:
> pop3-login: Disconnected (tried to use unsupported auth mechanism): user=<username at domain.it>, method=USER, rip=x,y,x,z, lip=x,y,w,z, session=<e5KkR5qto8hPAL9q>
> While, before upgrade, same user logged succesfully:
> pop3-login: Login: user=<username at domain.it>, method=PLAIN, rip=x,y,x,z, lip=x,y,w,z, mpid=62876, session=<dMRmGWCtFtJtdcy6>

The only thing that comes to mind is the pop3 issue where an auth attempt
after a failed auth attempt would always fail.  I'm not sure why the client
that's having issues is failing the first attempt (unless it tries an
unsupported mechanism first, and then tries to fall back to PLAIN).  Anyway,
there is a fix on the master branch.


You can try to patch the code with it and see if that helps.
2.3.12 and (if there is one) will have this fix.


mainframe, n.:
  An obsolete device still used by thousands of obsolete companies serving
  billions of obsolete customers and making huge obsolete profits for their
  obsolete shareholders. And this year's run twice as fast as last year's.

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