ssmtp stopped sending through Gmail mailhub

[Walter Garcia-Fontes]

Steps to reproduce:

Configure ssmtp to send through gmail following these instructions:
mailhub=smtp.gmail.com:587

<email address hidden>
AuthPass=MyPassword
UseTLS=YES
UseSTARTTLS=YES
rewriteDomain=gmail.com
hostname=localhost
FromLineOverride=YES

From the command line:
echo "Hi" | ssmtp -v "<email address hidden>"

What should happen?
Mail should be sent

What happens:
<-] 220 smtp.gmail.com ESMTP f2sm18698330wme.12 - gsmtp
[->] EHLO localhost
[<-] 250 SMTPUTF8
[->] STARTTLS
[<-] 220 2.0.0 Ready to start TLS
[->] EHLO localhost
[<-]
ssmtp: (localhost)

Mail is not sent. It was working perfectly for years and also in Ubuntu 19.04 since a couple of days ago.

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: ssmtp 2.64-8ubuntu2
ProcVersionSignature: Ubuntu 5.0.0-15.16-generic 5.0.6
Uname: Linux 5.0.0-15-generic x86_64
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
CurrentDesktop: Unity:Unity7:ubuntu
Date: Tue Jun 4 12:56:54 2019
InstallationDate: Installed on 2015-10-17 (1325 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: ssmtp
UpgradeStatus: Upgraded to disco on 2019-04-16 (49 days ago)
modified.conffile..etc.logcheck.ignore.d.server.ssmtp: [inaccessible: [Errno 13] Permission denied: '/etc/logcheck/ignore.d.server/ssmtp']
modified.conffile..etc.ssmtp.revaliases: [modified]
mtime.conffile..etc.ssmtp.revaliases: 2019-06-03T07:28:18.063128

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Raúl (kastays)]

I can confirm this issue. I've installed two virtual machines, one with Ubuntu 18.04 and another with 19.04. In the two machines I only have installed updates and ssmtp package. With the same configuration in both, the ubuntu 18.04 works correctly but the 19.04 not. The error is the same as Walter says.

[Walter Garcia-Fontes (walter-garcia)]

Currently ssmtp is unmaintained at Debian and so probably will disappear soon from the repositories:

https://wiki.debian.org/sSMTP

A very similar program to substitute it, already in the repositories, is msmtp:

https://wiki.debian.org/msmtp

The above setup works perfectly with this other package.