Arch Linux

Description:
When the sendmail binary is called by Dovecot's LMTP for sending an auto-response to the sender when a Vacation/OOO filter is enabled - the following repeated errors are found in the error log.

Jan 02 17:20:33 lmtp(me@domain.email)<13528><qg2bJ8MvTFrYNAAAUXb6+w>: Error: sieve: msgid=<CAE2c3QaHRrFCrHixwr4HfqtaOLSvKTUCPkj-2W3shzLnntcrOw@mail.gmail.com>: failed to send vacation response to me@gmail.com: <Failed to execute sendmail> (temporary error)
Jan 02 17:20:39 lmtp: Error: postdrop: warning: mail_queue_enter: create file maildrop/248933.10994: Permission denied

When I enable debugging I see:
Dec 29 21:21:38 lmtp(me@domain.email)<17187><UA2fMEQiR1ojQwAAUXb6+w>: Debug: program `/usr/sbin/sendmail'(17336) execution timed out after 30000 milliseconds: sending TERM signal
Dec 29 21:21:38 lmtp(me@domain.email)<17187><UA2fMEQiR1ojQwAAUXb6+w>: Debug: Mailbox <lmtp DATA local>: Opened mail UID=1 because: virtual size (Cache file is unusable)

Additional info:
* package version(s)
postfix 3.2.4-2
postfix 3.2.4-3

I don't know if this happened with 3.2.4-1. I started getting email notifications about the permission denied error around December 24th from what to me seemed like after a Dovecot/Pigeonhole update. So far, the Dovecot mailing list is not acknowledging that it is a problem with Dovecot or Pigeonhole. They're under the assumption that I have AppArmor or SELinux enabled, but of course none of my Arch hosts have these.

* config and/or log files etc.
The error logs just spit out repeated permission denied error lines as shown.

Steps to reproduce:
Install or upgrade to the latest Arch package releases for the following.
postfix 3.2.4-3
dovecot 2.3.0-1
pigeonhole 0.5.0-2

Create a Vacation/OOO rule such as:
# rule:[Vacation]
if true
{
vacation :days 1 :addresses "me@domain.email" :subject "Vacation" :from "noreply@domain.email" text:
Hello,

Thanks for your email. I am out of the office.
.
;
}

Have any sender mail the address with an enabled OOO sieve response and `tail -f /var/log/mail/mail.err` or the respective error log. Notice a continuous permission denied message in addition to the "Failed to execute sendmail (temporary error)".

Jan 02 17:21:33 lmtp: Error: postdrop: warning: mail_queue_enter: create file maildrop/725880.13530: Permission denied
Jan 02 17:21:39 lmtp: Error: postdrop: warning: mail_queue_enter: create file maildrop/250066.10994: Permission denied
Jan 02 17:21:43 lmtp: Error: postdrop: warning: mail_queue_enter: create file maildrop/726066.13530: Permission denied
Jan 02 17:21:49 lmtp: Error: postdrop: warning: mail_queue_enter: create file maildrop/250302.10994: Permission denied
Jan 02 17:21:53 lmtp: Error: postdrop: warning: mail_queue_enter: create file maildrop/726277.13530: Permission denied

Run: postfix check (no errors reported of any kind)

Invoking the `sendmail` command to send from the command line and from the vmail user is successful. Unfortunately the common fix described everywhere has no effect on this bug. For example:

systemctl stop postfix
killall -9 postdrop
chgrp -R postdrop /var/spool/postfix/public (group previously postdrop)
chgrp -R postdrop /var/spool/postfix/maildrop (group previously postdrop)
postfix set-permissions
postfix check
systemctl start postfix

This problem persists across multiple Arch hosts.