LinuxQuestions.org - Cannot access email via IMAP on Ubuntu 18.04 mail server

I've set up an email server using Postfix 3.3.0 on Ubuntu 18.04, on an EC2 instance. Sending emails to and from my server and external email services (eg gmail) is working just fine.

The only issue I've run into now is accessing my email through a mail client not on my server. I installed courier-imap so I could access my email through IMAP but it keeps failing.

I am trying to use Thunderbird in which I've entered (the equivalent of) the following settings:

Incoming: IMAP
Server hostname: mail.redd9.ca
Port: 143
SSL: None
Authentication: Normal password

Outgoing: SMTP
Server hostname: mail.redd9.ca
Port: 25
SSL: None
Authentication: Normal password

Username: Incoming: redd
Outgoing: redd

This gives me 'Thunderbird failed to find the settings for your email account. I tried tweaking the ports, authentication, etc but still got the same error, even after opening up all the ports on the EC2 firewall.

Output of postconf -n is below, would appreciate any advice.

Code:

alias_database = hash:/etc/aliases

alias_maps = hash:/etc/aliases

append_dot_mydomain = no

biff = no

compatibility_level = 2

home_mailbox = Maildir/

inet_interfaces = all

inet_protocols = all

mailbox_size_limit = 0

mydestination = mail.us-east-2.compute.internal, mail.redd9.ca, redd9.ca, mail, localhost.localdomain, localhost

myhostname = mail.redd9.ca

mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128

myorigin = /etc/mailname

readme_directory = no

recipient_delimiter = +

relayhost =

smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)

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_session_cache_database = btree:${data_directory}/smtpd_scache

smtpd_use_tls = yes

virtual_alias_maps = hash:/etc/postfix/virtual

Output of /etc/courier/imapd:

Code:

ADDRESS=127.0.0.1





PORT=143







MAXDAEMONS=40





MAXPERIP=20





PIDFILE=/run/courier/imapd.pid





TCPDOPTS="-nodnslookup -noidentlookup"





IMAPACCESSFILE=/etc/courier/imapaccess





LOGGEROPTS="-name=imapd"









IMAP_CAPABILITY="IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE"





IMAP_KEYWORDS=1





IMAP_ACL=1







IMAP_CAPABILITY_ORIG="IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA AUTH=CRAM-MD5 AUTH=CRAM-SHA1 AUTH=CRAM-SHA256 IDLE"





IMAP_PROXY=0







IMAP_PROXY_FOREIGN=0





IMAP_IDLE_TIMEOUT=60





IMAP_MAILBOX_SANITY_CHECK=1





IMAP_CAPABILITY_TLS="$IMAP_CAPABILITY AUTH=PLAIN"





IMAP_CAPABILITY_TLS_ORIG="$IMAP_CAPABILITY_ORIG AUTH=PLAIN"





IMAP_DISABLETHREADSORT=0





IMAP_CHECK_ALL_FOLDERS=0





IMAP_OBSOLETE_CLIENT=0





IMAP_UMASK=022





IMAP_ULIMITD=131072





IMAP_USELOCKS=1





IMAP_SHAREDINDEXFILE=/etc/courier/shared/index





IMAP_ENHANCEDIDLE=0





IMAP_TRASHFOLDERNAME=Trash





IMAP_EMPTYTRASH=Trash:7





IMAP_MOVE_EXPUNGE_TO_TRASH=0















SENDMAIL=/usr/sbin/sendmail





HEADERFROM=X-IMAP-Sender









IMAPDSTART=YES



MAILDIRPATH=Maildir