Dovecot not responding to external clients

[Alexander Dalloz]

Am 15.08.2019 um 00:34 schrieb Edwin Humphries via dovecot:
> Hi all
> 
> I have Dovecot on my Linux-Mint workstation, running IMAP for the 
> Thunderbird client thereon, but previously also for my phone and laptop 
> clients as well. Since upgrading to Linux-Mint 19, however, although the 
> Thunderbird client on the workstation works just fine, the other clients 
> can't connect. I've disabled the firewall, and nmap shows the ports 
> open, so it seems like some setting in the server. Can anyone help?

lsof -i :143
lsof -i :993

What does your mail logging report when the clients try to connect? 
Anything that blocks connections from outside the dovecot host itself?

>> Dovecot version is 2.2.33.2 (d6601f4ec)
>>
>> dovecot -n output:
>>
>> # 2.2.33.2 (d6601f4ec): /etc/dovecot/dovecot.conf
>> # Pigeonhole version 0.4.21 (92477967)
>> # OS: Linux 4.15.0-55-generic x86_64 Linux Mint 19.1 Tessa
>> 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"
>> ssl_cert = </etc/dovecot/private/dovecot.pem
>> ssl_client_ca_dir = /etc/ssl/certs
>> ssl_key =  # hidden, use -P to show it
>> userdb {
>>   driver = passwd
>> }
>>


Alexander