Avoid duplicate emails in the sent folder

Hello,

I have a webmail program, that I cannot configure to not save sent emails in the Sent folder. My emails to the SOGo team don't seem to reach the mailing list anymore.

So, I have no other choice to think the problem differently, and _maybe_ use Dovecot to fix this issue. Moreover, I think this could be useful for other email clients.

First, I have tried to use Sieve, but no success so far:

imapsieve_mailbox4_name = * imapsieve_mailbox4_from = Sent imapsieve_mailbox4_causes = APPEND, COPY imapsieve_mailbox4_after = file:/var/lib/dovecot/sieve/sent- checks.sieve

And this sieve script:

Message-ID header. require [ "variables", "environment", "duplicate", "imapsieve" ];

[…]

if duplicate :seconds 10 { discard; }

Otherwise, can I configure dovecot in a certain way, for instance create a virtual Sent folder. This would not save the email when appended, but still returns the list of sent emails ?

But this is not working. Any idea?

Thanks for your help!

André