Differences in "Delivered-To" header between deliver and LMTP

[Timo Sirainen]

On 11 Jul 2014, at 12:23, Charles Marcus <CMarcus at Media-Brokers.com> wrote:

>> Oh, that's annoying. Dovecot LDA doesn't actually add this header, it was your MTA that added it. But looks like I hadn't checked what the MTAs actually write to the header when I added this feature to LMTP, and nobody had mentioned this before either. I wonder if anybody's system breaks if I just change it now..
> 
> If you do this Timo, would you please also consider going ahead and adding the 20 or so lines of code you said it would take to also add support for the x-original-to header (this specific was in a private email to me while our support contract was active), as we discussed on this list - and you then discussed with Wietse, back in April or so of 2012:
> 
> http://dovecot.org/list/dovecot/2012-April/082585.html

The problem is still that it would require Dovecot LMTP to start advertising the DSN extension, which brings it more responsibilities. I'm still a bit scared of doing such change as it would need to be thought out well and to see what its impact would be for current MTAs. I'm especially worried that different MTAs would behave differently and we might need to add a setting to control what Dovecot needs to do.