Just an update, because there are currently several open bugs regarding smeserver-vacation being worked on (8772, 8774, 8776).
It seems the vacation script (/usr/local/bin/vacation) only parses the Subject: mail header field of an incoming mail into the $SUBJECT variable if the incoming mail's Subject field starts with a capital 'S'. I found eg. that in a mail sent from SOGo MUA, headers contain:
from: "Test2 User2" <test2@smetest.local>
subject: bla3
whereas in a mail sent from Horde MUA, headers contain:
From: test2@smetest.local
Subject: bla3
In the auto-reply to the mail sent from Horde, the $SUBJECT gets expanded, in the auto-reply to the mail sent from SOGo, it does not get expanded and the fallback "(NO SUBJECT)" is used instead.
I have opened
http://bugs.contribs.org/show_bug.cgi?id=8777 for you to follow up this issue.
Cheers,
Mats