Email rejected as Virus; Huge Email size; How to remove css content form content

Your software
My Mautic version is: 2.15
My PHP version is: 7.2.28

Your problem
I sent several email to my mailing list. Some of them where bounced off by SMTP server claiming it is a Virus. Other was kinder saying they did it because it was spam.

gmail discard my emails gracefully without informing me. It even didn’t get to the “promotions” folder.

host []
SMTP error from remote mail server after end of data:
552 5.2.0 981Ejk88ZikDf981Fj2TIF Virus infected message rejected.
Sending the same message from my Thunderbird passed.

I made small “hello world” message and send It to me. The mail came in at 6MB in size. I Download and installed “empty” email theme and did the same. The file size is 2MB.

The 2MB is composed from huge css file that is included in the message.

I want to remove it.

How can I do that?

Thank you!


Another mail bounced:

This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: host [] SMTP error from remote mail server after end of data: 551 5.7.6 Message rejected as virus (CM)

To answer my post -

I have a ads blocker in my Firefox browser. It injects two huge css files to every window opened.
Apparently it does that to the composer window also. The css files are caught and embedded into the mail message. Making it look suspicious to smtp spam filters.

The solution: Disable the adblocker plugin on Mautic sites.