Server running very slow and not responding

[chrisp8756]

Hello,
Running ISPconfig 2.29, I have 41 email accounts created on one domain, the accounts are very active. After about a week of having the domain on the server, now my server is running very slow and nothing is responding. I'm not sure where to even begin. The maillog file is 386,000 plus in size, it appears to me we don't have any problems with the server until those 41 accounts become active and it like kills the server. Not sure where to even began troubleshooting the issue.

Last night while the 41 accounts were idle the server was fine, and things worked like normal. As soon as the business opened and they started using the email accounts boom, running really slow and not responding. Any help would be greatly appreciated.