Postfix + Dovecot and the purpose of LMTP

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Postfix + Dovecot and the purpose of LMTP

Dennis Steinkamp
Hey guys,

i hope i am not bothering you guys lately with my rather stupid
questions about postfix on the mailing list.
There are tons of guides and how-tos out there and of course i try to
look for answers there first but apparently, there are so many
different ways of how things can be done, it`s sometimes very confusing
when your primary goal is to just understand how things work.
Please bear with me for a while, if the answer to my question is all to
obvious for the majority of you guys.

My question is about postfix and dovecot and how they interact with each
other.
As far as i know, you can let the MDA of Postfix handle mail delivery to
a certain directory and if that directory equals the mail_directory
you`ve set up in the dovecot configuration, there is no need for lmtp.
On the other hand, you can deliver the mails from postfix to the Dovecot
MDA through LMTP (or even LDA but nowadays everyone seems to prefer LMTP
cause its faster and easier to configure, right?)
so that Dovecot becomes responsible for delivering the mail to
mail_directory.
My first questions is, what are the benefits of letting Dovecot handle
mail delivery instead of the postfix mda?
If i go for the lmtp approach, directory related postfix directives like
virtual_mailbox_base etc. are totally ignored cause the responsibility
od delivering mails to  a certain directory is completly outsourced,
correct?

Thank you

Dennis



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Re: Postfix + Dovecot and the purpose of LMTP

Robert Schetterer-2
Am 06.01.2016 um 17:51 schrieb Dennis Steinkamp:
> My first questions is, what are the benefits of letting Dovecot handle
> mail delivery instead of the postfix mda?

i.e dovecot and postfix may hosted at different places/servers,
in real complex mail setups are used widely

> If i go for the lmtp approach, directory related postfix directives like
> virtual_mailbox_base etc. are totally ignored cause the responsibility
> od delivering mails to  a certain directory is completly outsourced,
> correct?

depends, i have

virtual_transport  = lmtps:inet:localhost:24
virtual_mailbox_base = /usr/local/virtual
virtual_minimum_uid = 1001
virtual_uid_maps = static:1001
virtual_gid_maps = static:1001

both postfix an dovecot have more data in sql
so its a question of "design" what you want

Best Regards
MfG Robert Schetterer

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Re: Postfix + Dovecot and the purpose of LMTP

Wietse Venema
In reply to this post by Dennis Steinkamp
The main difference is that with LMTP, Dovecot is in complete control
over the message store: how messages are stored, how they are
retrieved, per-user filters, per-user quotas, and so on. It makes
a lot of sense to split the responsibilities of mail handling.

(the use of LMTP instead of SMTP is an optimization; LMTP supports
per-recipient delivery statuses, which simplifies some problems
that would otherwise require one recipient per delivery).

        Wietse
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Re: Postfix + Dovecot and the purpose of LMTP

Dennis Steinkamp
Thank you very much Wietse and Robert. :)

Dennis

Am 06.01.2016 um 19:55 schrieb Wietse Venema:

> The main difference is that with LMTP, Dovecot is in complete control
> over the message store: how messages are stored, how they are
> retrieved, per-user filters, per-user quotas, and so on. It makes
> a lot of sense to split the responsibilities of mail handling.
>
> (the use of LMTP instead of SMTP is an optimization; LMTP supports
> per-recipient delivery statuses, which simplifies some problems
> that would otherwise require one recipient per delivery).
>
> Wietse