SMTP server not sending: NOQUEUE: reject: RCPT from unknown[] 451 4.3.0 : Temporary lookup failure – Too many mysql Connections

Jun 16th, 2012 | By | Category: Linux / Freebsd

So are you seeing this error message in thunderbird or evolution?  Chances are your smtp server isn’t able to connect to mysql properly as there are too many current connections for it to get in there.

To test this theory go into mysql on the server and type SHOW GLOBAL STATUS;

Chances are your going to see something like this near the end of that list:

Threads_connected                 | 151

Now while this could be an indication that you need to increase your global max connection setting( SET global max_connections = 180 ) it’s probably an indication, as it was in my case, that you have some processes that aren’t properly closing their mysql connection.  Because if you restart mysql and re-run SHOW GLOBAL  STATUS you’ll probably see something like this:

Threads_connected                 | 2


So while you can up your max connections in mysql, and then by editing your my.cnf file and looking for max_connections =  you should probably find out which process isn’t closing and solve that problem as upping your max connections will only prolong the inevitable.

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