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Email Mailboxes periodically max out connections with Exchange 2007


I have an issue where a set of Email Mailboxes periodically (daily) lose connection with Exchange with the following errors:

HelpSpot Error Log:
Cannot connect to [email address] #IMAP Errors-> Kerberos error: Unknown code krb5 195 (try running kinit) for [Exchange server];Retrying PLAIN authentication after AUTHENTICATE failed.;Retrying PLAIN authentication after A tasks.php 171

Which coincides with the Exchange message:
The number of simultaneous connections made by user [email address] has exceeded the limit (16).

Is there a chance that either HelpSpot or Exchange are holding onto connections longer than needed or some other configuration setting that I am missing? The odd part is that there are only 3-4 Email Mailboxes that lose connections out of around 20, and it is always the same ones yet I cannot see how they are configured differently at either end.

Any help would be greatly appreciated!

I should note: Swapping connections from using POP3:110 & IMAP:143 and visa versa generally restores the connection for the next 24 hours or so but this is a cumbersome daily chore.



HelpSpot doesn’t keep connections open, so it will only be running when tasks.php is run via Windows Schedule Tasks (or cron if you’re on linux). However, there can be a lot of connections not because of pop/imap but because of outbound email.

So say 3 emails come in during 1 tasks.php run, that will be one connection, however, those may generate many outbound emails for notifications, results of triggers, results of automation rules, etc. So I suspect a combination of the 4 mailboxes (each a connection) plus resulting outbound connections to send email are totaling up to more than your limit in whatever timeframe Exchange uses.

The best solution is to see if you can have your Exchange admin increase the limits for your email accounts. If you can’t, you could make sure you’re not making any connections you don’t need. For example, make sure your call tasks.php every minute and that it’s not setup for every 5 minutes for some reason. That way your connections are spread more evenly than if you wait and do a bunch of email at once.

Check that you aren’t sending notifications you don’t need, for example, if under each users preferences they have the ‘notify on unassigned new requests’ pref set. Do all those people really need email notifications of new requests. Are there triggers and rules sending emails that don’t need to be either directly sending emails or causing notification emails. Note, that with triggers and rules you can set the option to not have them generate notification emails.

Hopefully that helps a bit!


Thank you Ian. Yes, these email boxes do have multiple external notification triggers/email rules while the unaffected boxes do not. I am removing these and will let you know if the problem persists or if this is indeed the cause, which I suspect it is.

Much appreciated!