dropped: too many nonmail commands (last was "RSET")
Hello,
We have a client who utilises software designed for vets. A feature of that software is the ability to send authorised marketing emails to each individual client of the vet business.
They've been having issues with this software for some time and I've just managed to get to the bottom of what is happening.
The software works well with single emails; however, with bulk mail sent to individual clients Exim is dropping the connection following 10 emails with the error shown in the logs "dropped: too many nonmail commands (last was "RSET")". There are no preceding entries to the error so I have no idea if there were additional nonmail commands received prior to RSET.
I grepped exim and found the following:
exim -bP | grep 'smtp_accept_max.*[0-9]$'
smtp_accept_max = 100
smtp_accept_max_nonmail = 10
smtp_accept_max_per_connection = 1000
This appears to match up with smtp_accept_max_nonmail.
There used to be posts on the old forum that still show up on search engines but now throw 404s at cpanel sadly and other posts on the internet do not really help me understand what I can do (if anything) to remedy this.
Is this a software vendor issue in that their software is sending too many nonmail commands to exim following each individual piece of email it sends or is there some way of resolving this within Exim itself?
Their mailing list is in exess of 800 clients.
I'd be grateful if there's anyone that can offer advice on a setting I can use or if it needs to be relayed back to the software vendor.
Thank you.
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Hey there! Per the Exim docs at https://www.exim.org/exim-html-current/doc/html/spec_html/ch-main_configuration.html
"Exim counts the number of “non-mail” commands in an SMTP session, and drops the connection if there are too many. This option defines “too many”. The check catches some denial-of-service attacks, repeated failing AUTHs, or a mad client looping sending EHLO, for example. The check is applied only if the client host matches smtp_accept_max_nonmail_hosts."
so yes, it would seem to need to increase that value a bit to handle the mailing list that is being sent all at once.
You can do this in WHM >> Exim Configuration Editor under the Advanced tab. Right above the text "Section: BEGINACL" you'll see a blue button you can click called "Add Additional Configuration Setting" - click that, and you'll find the smtp_accept_max_nonmail option in the drop down.
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