Configure postfix mail server with outlook or Thunderbird mail client

I have successfully configured my email server with digital-ocean ubuntu 18.04 LEMP droplet and everything work fine so far. I can send & receive email and also successfully configured with round-cube webmail client. I used Mailgun as an SMTP relay.

But when I tried to connect to a mailbox in my mail server through outlook or Thunderbird, it keep on saying that the client failed to find the settings for the account. I tried to do the configuration manually and still giving me the same error.

Any help or suggestion would be appreciable.

Output of postconf -n

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
compatibility_level = 2
dovecot_destination_recipient_limit = 1
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
mydestination =, localhost.localdomain, localhost
myhostname =
mynetworks = [::ffff:]/104 [::1]/128
readme_directory = no
recipient_delimiter = +
relayhost = []:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps =
smtp_sasl_security_options = noanonymous
smtp_tls_note_starttls_offer = yes
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_recipient_restrictions = permit_sasl_authenticated permit_mynetworks reject_unauth_destination
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
virtual_mailbox_domains =
virtual_transport = dovecot

Output of dovecot -n

mail_location = maildir:/var/mail/vmail/%d/%n/Maildir
mail_privileged_group = mail
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext
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 {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
plugin {
  sieve = file:~/sieve;active=~/.dovecot.sieve
protocols = " imap sieve"
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  unix_listener auth-userdb {
    mode = 0666
    user = vmail
  user = dovecot
service imap-login {
  inet_listener imap {
    port = 143
service imap {
  process_limit = 1024
ssl_cert = </etc/dovecot/private/dovecot.pem
ssl_client_ca_dir = /etc/ssl/certs
ssl_key =  # hidden, use -P to show it
userdb {
  args = uid=vmail gid=vmail home=/var/mail/vmail/%d/%n
  driver = static
protocol lda {
  mail_plugins = " sieve"

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Did you figure it out ?

Hello Friend!

I was reading your question. I think the best answer of your question in this link -

Thanks !

Aanchal Rathore

Hey friend,

Great question! Most likely, based on that error provided, your email client is attempting to autoconfigure your email account. That might work under certain circumstances, but not in a case like yours. There should be an option to manually configure the IMAP/SMTP settings, and that would be the route to go.