Problems with new installation

[Steve Matzura]

I had Dovecot running very well on Ubuntu 14.04. Then I decided that 
since That version of Ubuntu was now out of support, I would build a new 
server on 18.04, which has been done.


I thought I could take the old dovecot.conf and everything in conf.d 
that had been customized and drop it in place, and everything would just 
work. That has proven not to be correct. The files that had been edited 
were the main /etc/dovecot/dovecot.conf, and in conf.d, 10-master.conf, 
10-ssl.conf, and 10-mail.conf. I have restored the original 
package-supplied versions of these files and restarted Dovecot, but 
still no one can connect. Here's my configuration, with the version 
number at the top:


# 2.2.33.2 (d6601f4ec): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.21 (92477967)
# OS: Linux 4.15.0-64-generic x86_64 Ubuntu 18.04.3 LTS
auth_debug = yes
auth_debug_passwords = yes
mail_debug = yes
mail_location = mbox:~/mail:INBOX=/var/mail/%u
mail_privileged_group = mail
namespace inbox {
   inbox = yes
   location =
   mailbox Drafts {
     special_use = \Drafts
   }
   mailbox Junk {
     special_use = \Junk
   }
   mailbox Sent {
     special_use = \Sent
   }
   mailbox "Sent Messages" {
     special_use = \Sent
   }
   mailbox Trash {
     special_use = \Trash
   }
   prefix =
}
passdb {
   driver = pam
}
protocols = " imap lmtp"
userdb {
   driver = passwd
}
verbose_ssl = yes


The edits that were made to the aforementioned files were not actually 
done by me, so I can't explain why certain choices were made, except for 
obvious ones such as SSL key paths. But I figured the system should work 
at least on a vanilla configuration.


Postfix is also involved in this, so the problems may not at all be with 
Dovecot, but with Postfix. I think I just need to draw the line between 
them and be able to know definitely that at least one half of the system 
is functioning correctly so I know I can mark that part as working, and 
proceed with debugging the other. My bet at this point is that it's not 
a Dovecot problem, but I'm not clear on how to determine this, with or 
without my changed files.


Thanks in advance.