My ISPconfig3 install started producing monit notices a few days ago. They come in pairs with a "success" notice first followed by a "fail" notice. The "fail" notice looks like this: Code: Date: Mon, 22 Jun 2015 14:14:21 Action: restart Host: host.mydomain.com Description: failed protocol test [SMTP] at INET[localhost:10024] via TCP -- SMTP: error receiving data -- Resource temporarily unavailable It's been running fine for months with no problems. I'm using Dovecot and ISPConfig V18.104.22.168p8. Any ideas?