Thanks for the tips, however I've taken an easier route as I don't have sufficient privileges to change those PHP.ini settings.
I had to stop using Gmail in the past as they changed their authentication requirements.
Then you came along with Zhen mailer, which got the mail working again on PHP7.4 using the default PHP mail 
However, by setting ones Gmail account to use TFA and an application password, putting that password in the SMF STARTTLS-SMTP mail settings works fine on PHP8.0.
Thanks and enjoy the rest of your day, you deserve it 

When using PHP FCGI there will likely be 2 php.ini files.
One is the default which is available when installed but when running multiple PHP versions a secondary php.ini is created.
The secondary is the one that takes affect.
This is shared hosting? Is your only way of accessing the php.ini file via a control panel?

Also set your mail.log path from the php.ini file.
Both the error_log & mail.log file paths should be created plus Apache should have ownership + permissions to use the file(s).

Is it only Zhen Mailer that isn't working?
Does your PHP mail work just using SMF itself?
Admin -> Mail -> Send Test

If it doesn't work at all only with PHP 8.0 then something is awry with a config file native to that PHP version.

Check your admin email for spam and/or all mail.
If the mail headers aren't correct then it will be sent through as spam.

Hi again,
Well I've checked both PHP configs and they look the same.
For some reason, my php  error log has not updated for 2 yrs, even though error logging is enabled.
Something else to look into at some point 
I have a test SMF forum running 2.12 on the same shared hosting server and that sends mail fine when running PHP8.0 using default PHP mail type, so I don't see how the server config can be at fault.
Guess I'll have to try and get the logging sorted to see what the issue is.
I'll report back if I finally get the mail working.
Many thanks for your time.

Create a top HTML type block with this content:
<div style="display: inline-flex;padding: 0rem;width: 100%;position: relative;overflow: hidden;align-items: right;justify-content: right;" id="google_translate_element"></div>
<script type="text/javascript">
function googleTranslateElementInit() {
  new google.translate.TranslateElement({pageLanguage: 'en'}, 'google_translate_element');
}
function insertMyGoogleTranslate() {
    var mySmfDiv = document.getElementById("google_translate_element");
    mySmfDiv.style.paddingRight = "0.3rem";
    mySmfDiv.style.paddingLeft = "0.3rem";
    mySmfDiv.style.lineHeight = "2rem";
    mySmfDiv.style.height = "2rem";
    mySmfDiv.style.overflowY = "hidden";
}
if (window.addEventListener)
    window.addEventListener("load", insertMyGoogleTranslate, false);
else
    window.attachEvent("onload", insertMyGoogleTranslate);
</script>
<script type="text/javascript" src="//translate.google.com/translate_a/element.js?cb=googleTranslateElementInit"></script>

Hide the title & body of the block.
(Style Options ->  checkboxes for: No Title + No Body)

This sounds as though some PHP settings need to be adjusted for PHP 8.0.
Compare your PHP 7 php.ini file to your PHP 8 php.ini file.

Check to see if these variables are set to the same values:
openssl.cafile
curl.cainfo
sendmail_path
error_log

Your PHP error log will likely show whatever error is occurring (not the SMF error log).

If you make changes to that file, you'll need to reset Apache afterward.

---

More than likely it's the sendmail_path that is not configured correctly.
Make sure you remove the semicolon prior to the setting when you want to use/adjust it because that acts as a comment & is ignored when a line starts with it.

Hi,
Well tried your 1.3.2 version and good and bad news. Good news is that it no longer shows an error.
Bad news is that it is still not sending any mail. This is with the mail type set as the default PHP setting.
Reverted back to PHP 7.4 and mail is then sent OK.
No errors are seen in the Admin logs.
Thanks for the quick response anyway 

Hmm.. some posts still make it past my spam mod.
I'll have to look at them more closely to see what's going on there.
The post I just deleted is in the recycle board but I can't find it at the moment 

Thanks.

Version 1.3.2 is now available which includes a fix for what was reported.

Can you give the file & line that the error showed in the log?

Nevermind.. I found it right away when testing on PHP 8.
I will release a fix for it shortly & thanks for the report.

Chen any chance you can whip up a code for changing the languages in a  portal block