I admit i was wrong about saying things were not working email wise , mainly it was my head to which, was not. It turns out the problem was a faulty SPF record in my hosting. Sorry :(

The smtp component is working fine now , it had to do with email records , namely a SPF record. Thanks for guidance, all.

@Graham

Please download SMTP component 6.4 and try that with following guideline
https://github.com/opensource-socialnetwork/SMTP/wiki/How-to-obtain-token-from-gmail

This is only valid for gmail if you have other provider, my answer is same as Michael, try to isolate all this from OSSN and use some SMTP client to test it first.

Yeah, just frustrating, as we've been at this stage already one week ago. See
https://www.opensource-socialnetwork.org/discussion/view/6086/non-activated-user-notifier

BTW, it's not only gmail not accepting mails by the yiffzred server. I tried to register using my [email protected] address some days ago and received no mail, either. Hence I'm wondering whether this smtp server is sending mails at all?

And in order to verify I'd try to isolate all this from Ossn and use a different SMTP client like Thunderbird with the same credentials shown below in this thread and send a testmail to a gmail address or the address of mine.

I am done here as you seems not following the point.

If SMTP is sending to the one domain but not other you need to contact your SMTP provider

Where is the file for the basic php mailer located in cpanel? Or the location of the php file?

You are using SMTP to send emails and it appeared by this thread you are using Gmail. Now if mails going to proton mail not to gmail its time to contact Gmail team. You need to see if email exists in sent folder. Ossn can't do anything.

My hosting company says that the blacklist from that specific blacklist doesnt effect my email deliverability

That i very interesting, Eyad i wonder if i change my ip what problems will arise from my setup , but i read dont they remove you after 7 days ?

I tried to check your mail server's IP (the mailserver is mail.yiffzred.com, I think) to see if it's listed in a blacklist or not, and it's listed in the UCEPROTECTL3 blacklist. This maybe the problem. You may try getting a new IP or something...