We’re on Mautic 6.0.2
We send emails via an SMTP relay. The test email is successfully sent via settings and the test email arrives in the test mailbox.
I have a test contact with the same email address. I go there, click the Send email button. From name and address default to the contact I’m sending the email to, so I change these to Mautic’s display name and email address. Draft a simple email then hit send. I get Internal Server error 500 message.
mautic.prod.log has this
[2025-07-17T03:29:54.836309+00:00] mautic.CRITICAL: Uncaught PHP Exception TypeError: “Mautic\CoreBundle\Helper\InputHelper::minifyHTML(): Argument #1 ($html) must be of type string, null given, called in /var/www/html/app/bundles/EmailBundle/Helper/MailHelper.php on line 1224” at /var/www/html/app/bundles/CoreBundle/Helper/InputHelper.php line 506 {“exception”:“[object] (TypeError(code: 0): Mautic\CoreBundle\Helper\InputHelper::minifyHTML(): Argument #1 ($html) must be of type string, null given, called in /var/www/html/app/bundles/EmailBundle/Helper/MailHelper.php on line 1224 at /var/www/html/app/bundles/CoreBundle/Helper/InputHelper.php:506)”} {“hostname”:“mautic”,“pid”:6865}
I close the popup window of the 500 error message. Instead of using my handwritten content, I select an email template to use, then send the email. I get a different error message
Failed to send to [email address]: Expected response code “250/251/252” but got code “550”, with message “550 5.7.1 Command rejected”.
This email address is the same that works fine when testing via System settings.
prod-[date].php log file has the same error message. No further details.
I don’t have access to the logs of the SMTP relay.
I then tried the following. Create a segment that targets this same, one single contact. I then created a campaign that sends a transactional email. This step uses the same email template as above. This email is not sent either. All I get is a small red exclamation mark in the campaign.
As the results contradict, I’m not sure where to next. I’d appreciate some help.
Cheers,
Zoltan