SASL authentication no mechanism available

When sending email from postfix mail sever that use mailgun for relaying mails, i get error

Jan 4 03:16:06 serverok-vm postfix/qmgr[22652]: 795731A8D: from=, size=820, nrcpt=1 (queue active)
Jan 4 03:16:06 serverok-vm postfix/smtp[24050]: warning: SASL authentication failure: No worthy mechs found
Jan 4 03:16:06 serverok-vm postfix/smtp[24050]: 795731A8D: SASL authentication failed; cannot authenticate to server smtp.mailgun.org[34.237.7.101]: no mechanism available
Jan 4 03:16:06 serverok-vm postfix/smtp[24050]: warning: SASL authentication failure: No worthy mechs found
Jan 4 03:16:06 serverok-vm postfix/smtp[24050]: 795731A8D: SASL authentication failed; cannot authenticate to server smtp.mailgun.org[34.232.180.42]: no mechanism available
Jan 4 03:16:06 serverok-vm postfix/smtp[24050]: warning: SASL authentication failure: No worthy mechs found

On checking postfix mail queue, the mail is stuck in queue

root@serverok-vm:~# postqueue -p
-Queue ID- --Size-- ----Arrival Time---- -Sender/Recipient-------
795731A8D       820 Wed Jan  3 21:38:20  [email protected]
(SASL authentication failed; cannot authenticate to server smtp.mailgun.org[54.164.235.211]: no mechanism available)
                                         [email protected]

-- 1 Kbytes in 1 Request.
root@serverok-vm:~# 

The problem is fixed by installing libsasl2-modules.

On Debian/Ubuntu

apt-get install libsasl2-modules

On RHEL/CentOS

yum install cyrus-sasl-plain

Now restart postfix.

service postfix restart

• mail
• Transnational Email Providers
• postfix