In ~/.muttrc:
<code>
set hostname=ircnow.org
set editor=nvi
set imap_user=user123@ircnow.org
set imap_pass="pass123"

set folder=imap://$imap_user@imap.ircnow.org

set spoolfile=+INBOX

set imap_check_subscribed
set header_cache=~/.cache/mutt
set message_cachedir="~/.cache/mutt"
unset imap_passive
set imap_keepalive=300
set mail_check=120

set record=+Sent
 unset record
set my_pass="pass123"
set my_user='user123@ircnow.org'
set realname='user123'
set from=user123@ircnow.org
set use_from=yes

set smtp_url=smtp://$my_user:$my_pass@ircnow.org:587
set ssl_force_tls=yes
set ssl_starttls=yes
</code>