We have a service partner who's operating ISPConfig on our servers. Everything worked perfect until we migrated to new servers. Since migration, on our new servers, SMTP is down very frequently (1-2 times a week) and it's always the SASL not responding properly. In the monitoring (provided by service partner) SMTP and SASL are shown as functional, but they aren't. As soon as I try to send a mail through SMTP, an error message appears like "wrong user name / password". Of course they're correct. After a restart of the SASL service, everything works as desired. For a few days. Since we're in this situation for more than 2 months now and this situation is ruining our company, I would like to ask you guys, if you can help me with this problem with only these few information. Otherwise, what information would be helpful, how can we identify and solve the problem? Every help would be appreciated...! Thank you very much in advance.