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 postmaster@mailout.serverok.in
(SASL authentication failed; cannot authenticate to server smtp.mailgun.org[54.164.235.211]: no mechanism available)
info@serverok.in
-- 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