Too Many Concurrent SMTP Connections

I’ve got a fairly complex setup, and have been running without issues for some time.

I’ve got about 20 domains on ghost, with between 1-5 accounts per domain. Some accounts use webmail, some thunderbird, some other clients, and some are automated systems, like voicemail to e-mail, server notifications, or web contact forms.

Lately, some users are reporting an error when trying to send messages of “too many concurrent SMTP connections” which often times resolves itself within a few minutes. This week, our PBX stopped sending voicemails for several hours, and the logs showed the same error.

I’ve done all the basic checks on volume for all of the automated systems, and nothing seems out of the ordinary.

Is this just a scaling issue you guys are working on, or is it more likely I’ve got a rogue mail client out there?

Any suggestions on what next steps I should take to get to the bottom of this would be appreciated.

Hey friend,

I’m very sorry about that, but thank you for reporting it to me. I have a maintenance window scheduled tomorrow that should take care of this. You can follow it here:

The server is buckling under the pressure of the inbound abuse and I’ve been trying to keep it under control by hand, but it isn’t enough. This should be the resolution.


Just glad to know I didn’t have to hunt down a user :slight_smile:

Maintenance complete, expecting a huge load to be taken off of exim.

This problem has started to occur for me in the past few weeks.
It’s made worse by a bug (mis-feature) in Thunderbird that causes the msg to be placed in the Sent folder rather than drafts. The devs say this is due misconfigured SMTP server. No idea if that’s true.

I found your home IP address and ran it through the exim logs on the Friday server. I could not find any recent (8/22 to 8/26) occurrences of your IP address being refused connection to exim. Digging back further I’m more prone to missing something but I didn’t see anything either. However, I do see your IP making upwards of 71 simultaneous SMTP connections as indicated by the logs (TCP/IP connection count = 71). That sounds like a bugged email client to me. As far as the email client writing an email to the Sent folder that wasn’t sent, that’s entirely email client behavior as our server doesn’t write emails to the sent folder at all.