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?

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
}