421 #4.4.5 Too many connections from your host

Question:

I get this error from my SMTP server:

421 #4.4.5 Too many connections from your host

What does it mean?

Answer:

The “too many connections from your host” error is the text of the error message that is coming back from the SMTP server. It indicates that the SMTP server has a limit on how many simultaneous open connections it will accept from a single IP address. There must have been other threads or processes (or applications) with open connections to the same SMTP server that caused you to exceed the limit.