Email error log when sending a bulk email fills up with errors which includes every so often the below message

Amazon SES, SMTP Error Response: 421 Connection closed by server. Maximum message count per session reached

 

investigation led to this topic here

https://repost.aws/questions/QUw5qK9rBFSKqXvW5a-nAteg/amazon-ses-smtp-error-response-421-connection-closed-by-server-maximum-message-count-per-session-reached

 

it says there may be a new limit of 350 calls from 19 Nov 2024 which fits in with the same date that they appeared in my email error log

 

Anyone else sending over 350 emails seeing this problem?

 

Edited December 1, 2024Dec 1 by sound

Don't use SMTP... it can slow down performance when you have very large topics as a result of notifications, and there are situations like this. 

There are a few third party plugins that leverages the APIs to send mail through SES using the API.  

For example, @Jon Erickson has one that I've personally used that is fantastic and has worked great...

https://store.deschutesdesigngroup.com/buy/0182a1f0-48ea-4438-9b40-293441be9f85

@stoo2000 also has one as well.  I've not personally used it, but including a link for you.

https://ipb.silvesterwebdesigns.com/file/9-mail-bouncer/

 

Don't use SMTP... it can slow down performance when you have very large topics as a result of notifications, and there are situations like this. 

There are a few third party plugins that leverages the APIs to send mail through SES using the API.  

For example, @Jon Erickson has one that I've personally used that is fantastic and has worked great...

https://store.deschutesdesigngroup.com/buy/0182a1f0-48ea-4438-9b40-293441be9f85

@stoo2000 also has one as well.  I've not personally used it, but including a link for you.

https://ipb.silvesterwebdesigns.com/file/9-mail-bouncer/

thanks, that's something to consider, ideally once v5 out

a quick and dirty fix appears to be comment out the return line  99 in smtp.php

 

public function connect( $checkSsl=TRUE )
    {
        /* Do we already have a connection? */
        if( array_key_exists( $this->connectionKey, static::$smtp ) )
        {
        ///nov2024    return;
        }

 

once done a 6k newsletter sent without error and the edit sort of validates this statement

Reset SMTP connections: Your suggestion to reset the SMTP connection before retrying to send a message that received this specific error is excellent. This will start a new session and should allow you to continue sending. It's a good practice to reset the connection after receiving this error, and it may indeed be beneficial to do so for other 4xx errors as well.

@Marc    maybe another forum be better suited

Im not sure how resetting a connection would stop you having over 350. Am I misunderstanding something?

 

 

Im not sure how resetting a connection would stop you having over 350. Am I misunderstanding something?

 

as far as I can make out the below happens

 

when you hit the 'new' limit of 350 messages, aws returns an error but my site doesn't close the SMTP  connection and so any following message sends from my site fails till the next time out

 

by commenting out the above line - my site now asks for a new connection each time the connect routine runs and so all the following emails after the error are always sent

 

as said it for me it seems a quick and dirty fix that has got my 6k+ newsletter sending with no errors

the link posted in the op has more technical info and recommendations

 

 

 

 

Edited December 2, 2024Dec 2 by sound

Added a bug report 🙂

 

Added a bug report 🙂

Has this been patched yet? According to my log, I just experienced this Wed, and it stopped at 350. A couple of others stopped at different points

 

Has this been patched yet? According to my log, I just experienced this Wed, and it stopped at 350. A couple of others stopped at different points

Not as of yet, no

 

Not as of yet, no

Okay. thank you. I’m guessing it's not in the 4.7.20 update as that is as beta 5 already, I suspect, will be released soonish. So the monthly update after that? a patch?

Or should I go in and mess with the file as suggested above?

Its not in 20, and would be in a future release, is all I can say at this point. It will not likely be in a patch.