[Dovecot] Sieve vacation reply problem (Dovecot+Sieve/Sendmail/Horde)

[Stephan Bosch]

On 8/21/2013 7:51 PM, megodin at inboxalias.com wrote:
> [mail.err] dovecot: lda(exampleuser): Error: sieve: original envelope recipient address 'exampleuser at dovecot_localhost' is unparsable
>

This is the core of your problem. The '_' is not an allowed character 
according to the SMTP `Domain' syntax 
(https://tools.ietf.org/html/rfc5321#section-4.1.2). The current 
implementation of Pigeonhole follows that quite strictly for parsing 
envelope addresses.

I think I'll make this a bit more lenient in the future, since you're 
not the first to complain about things like this (e.g. space characters 
in unquoted local part).

Regards,

Stephan.