Please check the From header, there should be no “.localhost” suffix or is it also in the From header?
From: sender@domain.tld
Do you get a bounce message? It may include more information.
Please also check the history in Rspamd, it should also show the headers and maybe some more helpful info.
Is DKIM, SPF etc. working? You could check by sending a mail, see Port25’s Authentication and Spam Assassin Tool | Postmark
Thanks for testing, did you enter the mail address in the right field? See also Roundcube vacation / autoreply / out of office email plugin, how to find / enable? - #28 by ansh
EDIT:
Here sending a mail from gmail to my NethServer and receiving the vacation mail in GMail works even without the dovecot change.
In Rspamd history it shows:
[unknown] markus@domain.tld
The “mail from” is correct but the envelope is empty.
Maybe the issue is at the smarthost? Do you use Gmail as smarthost?
Did you enter the mail address manually in the SOGo vacation settings, please try to use the default mail or the suggested one.
