SSMTP fails after migrating to Buster

Question

SSMTP was working for years now on my RPi - latest on stretch. Now I migrated to buster - and after this step it now fails.

$  cat /etc/ssmtp/ssmtp.conf
root=user@mydomain.com
mailhub=smtp.gmail.com:587
hostname=localhost
UseSTARTTLS=YES
AuthUser=user@gmail.com
AuthPass=very_secret
FromLineOverride=YES

$ echo "MailBody"|mail --debug-level=3 -s "My Subject" mailaddress@domain.com
mail: sendmail binary: /usr/sbin/sendmail
mail: source=system, name=user, passwd=x, uid=1001, gid=1000, gecos=user,,,, dir=/home/user, shell=/bin/bash, mailbox=/var/mail/user, quota=0, change_uid=1
mail: source=system, name=user, passwd=x, uid=1001, gid=1000, gecos=user,,,, dir=/home/user, shell=/bin/bash, mailbox=/var/mail/user, quota=0, change_uid=1
mail: mu_mailer_send_message(): using From: user@localhost
mail: Sending headers...
mail: Sending body...
mail: /usr/sbin/sendmail exited with: 1
mail: progmailer error: Process exited with a non-zero status
mail: cannot send message: Process exited with a non-zero status
mail: source=system, name=user, passwd=x, uid=1001, gid=1000, gecos=user,,,, dir=/home/user, shell=/bin/bash, mailbox=/var/mail/user, quota=0, change_uid=1

$ echo $?
36

I have a lot of shell-scripts sending mails with commands like:

echo "MailBody"|mail -s "My Subject" emailaddress@domain.com

=> so if SSMTP is no longer supported, I would neeed a solution following that syntax ...

thanks for any help!

Answer 1

I fixed this by switching away from ssmtp (which some sources say being unmaintained) to msmtp (https://wiki.debian.org/msmtp).

This could or could not apply to you, try to check the error code by sending an email directly via /usr/sbin/ssmtp -v ...., I had exit 36 (echo $? to get the code).

If you are in a similar situation and want to give msmtp a try, these the steps I followed:

Install:

$ sudo apt remove ssmtp
$ sudo apt install msmtp msmtp-mta

Configure (I'm not configuring GMail, I use Dreamhost email service, so your details might be different):

$ cat /etc/msmtprc 
# Set default values for all following accounts.
defaults
auth           on
tls            on
tls_starttls   off
tls_trust_file /etc/ssl/certs/ca-certificates.crt
logfile        /tmp/msmtp.log

# Raspberry Pi
account        rasp
host           smtp.dreamhost.com
port           465
from           raspberry@<REDACTED>
user           raspberry@<REDACTED>
password       <PLAINTEXTPASSWORD>

# default account
account default : rasp

For comparison, this was my /etc/ssmtp.conf file:

root=postmaster
mailhub=smtp.dreamhost.com:465
AuthUser=raspberry@<REDACTED>
AuthPass=<REDACTED>
UseTLS=YES
UseSTARTTLS=YES
TLS_CA-File=/etc/ssl/certs/ca-certificates.crt
hostname=<REDACTED>.org
FromLineOverride=NO

Set msmtp as default MTA. I've added the last line to my mail.rc file:

$ cat /etc/mail.rc
set ask askcc append dot save crt
ignore Received Message-Id Resent-Message-Id Status Mail-From Return-Path Via Delivered-To
set mta=/usr/bin/msmtp

[NOTE]: There is also an issue with msmtp in that it's not populating automatically the "From:" header in the message so emails get rejected, to fix it, when calling mail make sure to do it manually:

echo TEST | mail -a "From: raspberry@<REDACTED>" --debug-level 10 -s '[rasp] server' <REDACTED>@gmail.com

This makes email sending work again from my Raspberry Pi on Debian buster/sid.