It looks like gmail has increased it's spam detection furiosity. We have many complaints from customers having their e-mail sent to their servers bouncing back.

Most of the time it was because they didn't set a correct SPF for their domain. It was getting through a week ago (probably to spam box though) but now it is bouncing right away.

It is possible they alsochanged something about the message message-id header checking. We don't have this issue though,

I guess it's because we're using outgoing gateways and it is adding a message-id header if it's missing.

AFAIK message-id can be either generated by the mail client submitting the mail to the server, or if missing the mailserver should add one.

I did a test sending a mail from emClient with SMTP through smartermail and on gmail side the message-id looks like:

<em06326e16-c065-47e8-9fdc-3b3b9aacb8eb@19e41120.com> 

Looks to me like emClient add a message-id.

Now if I do the same test with SM webmail the message-id looks like:

<7e838ded6dcc4d47be15b0c0e417759b@mydomain.com> 

This one looks generated by SmarterMail (or maybe our gateway, not sure at this point)

On your side, does all messages to gmail get rejected or only some ?

If it's only some messages, is there a pattern that could emerge, like it depends if it's sent with SMTP, webmail, MAPI, EAS ?

Can you send a mail to another non-gmail address to check the message-id in the received message's source  ?

BTW it seems there is another thread ​about this subject:

Your posting was very helpful.

I reviewed the rejected messages.

I di a second look at the message id in each rejected message.

I now see the problem.

The message id reads as...

Message-ID: <fcfa03b5f5ee47fbb46ae4403b174ee8@com> 

...instead of...

Message-ID: <fcfa03b5f5ee47fbb46ae4403b174ee8@mydomain.com> 

I also sent test messages from the SmartMail web interface to test accounts I have at yahoo.com and gmail.com. 

The message id for all of the test messages were correctly formatted and included the complete domain name.

The messages with the incorrect message id are all being sent to SmartMail via Dimac JMail in an ASP application. (The ASP application has been running for over 17 years using Jmail.)

I am looking at JMail now for anything related to message id creation.

Regarding...

But what if the message-id added by the email client is damaged, incomplete, or junk?

Example:  Message-ID: <105c8f319ef74f63a8d2202b1a55dcc7@com>

If the message-id is malformed I want SmarterMail to correct it.

After updating to Build 8250 the problem still occurs.

Hello Douglas :-) The message-id you've included for reference is not a malformed message-id, and fulfills the RFC requirements implemented by Gmail in that it is a unique ID and has been appended by SmarterMail due to it not being appended by the sending client. 

With that being said, I think SmarterMail would likely append a proper message-id if the one included is malformed or otherwise unusable. Do you have a specific example of that I could use for testing?

Just a quick followup for you on this! I've been made aware that an invalid/malformed message-id appended by a client will not be corrected or replaced by SmarterMail. This reasoning is actually detailed quite nicely here on this post by Sébastien Riccio: