After 1,5 year with working mail server on Ubuntu 14.04 I've experienced strange amavis logs listed below: http://pastebin.com/RwbNw78f
Mail server is: Postfix + Dovecot + MySQL + Amavis + ClamAV + SpamAssasin deployed with recipe https://www.exratione.com/2014/05/a-mailserver-on-ubuntu-1404-postfix-dovecot-mysql/
After many 'googling' don't find any fix...