$ telnet smtp.example.com 587
Trying 127.0.0.1...
Connected to smtp.example.com.
Escape character is '^]'.
220 smtp.example.com ESMTP Postfix (Debian/GNU)
EHLO test
250-
250-PIPELINING
250-SIZE 10240000
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
QUIT
221 2.0.0 Bye
Connection closed by foreign host.

set ssl_starttls=yes
set ssl_force_tls=yes

set imap_user = "user@example.com"
set imap_pass = "!HASHEDPASSWORD!"
set folder = imap://mail.example.com/
set spoolfile = imap://mail.example.com/INBOX

# SMTP user auth
# # fill in the right user and pass based on your setup
# # protocols: smtp for TLS (25/587), smtps for SSL (465)
set smtp_url = "smtp://$imap_user@mail.example.com:587"
set smtp_pass = "$imap_pass"

# Where to save copies of outgoing mail
set record = '+Sent'

set from = "user@gmail.com"
set realname = "user"
set imap_user = "user@gmail.com"
set imap_pass = "pwd"
set folder = "imaps://imap.gmail.com:993"
set spoolfile = "imaps://imap.gmail.com/INBOX"
set postponed ="+[Gmail]/Drafts"
set header_cache =~/.mutt/cache/headers
set message_cachedir =~/.mutt/cache/bodies
set certificate_file =~/.mutt/certificates
set smtp_url = "smtps://user@gmail.com@smtp.gmail.com:465/"
set smtp_pass = "pwd"
set move = no
set imap_keepalive = 900

set ssl_starttls = no
set smtp_url = "smtp://user@example.com@mail.example.com:587/"
set smtp_pass = "password"

set ssl_starttls = no    # yes/no, but apparently yes is default.
set ssl_force_tls = yes     # yes/no
set smtp_authenticators = "login"   # set or not set

set smtp_url = "smtp[s]://..."   # smtp or smtps
set certificate_file = "~/.mutt/certificates"    # some recommends creating the file first: mkdir ~/.mutt && touch ~/.mutt/certificates

set ssl_verify_host = no    # yes/no
set ssl_verify_dates = no    # yes/no