After updating to 2.7.3+build.2022.09.05.15.16.54.d36b7aff3 version of CB, when someone registers as a new member, the email they receive is in Plain Text, rather than HTML. I've verified that the Registration tab in Configuration has HTML set as "Registration Email HTML YES". This has been verified and tried on two different systems with the same result. As a result, the Confirmation Link that is supposed to be in the email to verify the email address of the registrant comes through as embedded code, rather than a clickable link.

Additional information:  the culprit was PHP 8. Neither PHP 8.0 nor 8.1 will work. I had to go back to 7.4.30 to get it to work right.

When do you expect CB to be compatible with PHP 8?

You've misunderstood my question.

The format of the link is not the problem. It's the format of the email itself. It is displayed in plain text with HTML code showing because the email clients are unable to translate the message as formatted.

Because I'm not sure how HTML code may be displayed on this forum, I've attached a .txt file with an illustration of the problem. The top portion of the attachment shows the code as generated by CB when using PHP 7.4.30. That code is correctly translated by all email clients so that the HTML-coded email is displayed correctly, with operable hyperlinks included. The lower portion of the attachment shows the code as generated by CB when using PHP 8. That code is incorrectly translated by email clients so that the message is not identified as an HTML email, so the plain text display shows the code and hyperlinks are not clickable.

The problem showed up in Outlook 2019 (not Outlook.com), AOL, RoundCube, and Horde. It does not show up when sending/receiving emails using the mail server outside of CB using any client we've tried; however, I don't know what you mean by "Joomla emails" since we don't send/receive emails from within Joomla unless they're generated by CB.

To recap:  The system-generated emails associated with Registration within CB chosen to be formatted as HTML, rather than plain text. When we are using PHP 7.4.30, everything works fine, and the emails are received by all email clients as properly coded HTML emails. When we change to any PHP 8 version (8.0 or 8.1) and change nothing else, when the emails are received, they are recognized by the receiving client as plain text, displaying the HTML code instead of hypertext links or other HTML formatting (color, bold, underline, etc.). When we switch back to PHP 7.4.30 without changing anything else, the Registration emails are displayed properly again.

When we format HTML emails using a variety of clients but using the same mail server on the same site where CB is installed (as well as other servers), changing the PHP version does not affect those at all. Only those automatically sent through CB during the registration process.

Any other ideas on how we can test it?