> On 10 Sep 2018, at 0.05, Andreas Thienemann <[email protected]> wrote:
>
> Following the robustness principle it feels to me that it would make sense
> for dsync to disregard a duplicate header from a remote server and only use
> the first occurence.
>
> Would that be a good approach to the problem? Now that I understand the
> problem I am having, I can just workaround it but it seems to me that dsync
> should handle this case better.
>
Currently dovecot does rely on remote to send valid RFC-compliant headers. But
you are not alone, we have seen similar problems with mixed header fields on
some legacy servers on the migrations we have performed.
I have found dsync_hashed_headers setting as a good workaround for migrating
mails from broken imap servers. As per RFC Message-ID should be unique and we
have safely used setting dsync_hashed_headers=Message-ID to migrate the
problematic users away from the broken servers.
Sami
