Thanks again, krileon.

Regards,
Fabio.

How did you get rid of the warning.
I'm facing the same troubles.

i'm using a free Let's Encrypt certificate on a shared host.

thanks for your help

Hello jjsjjs,

I got rid of the problem by changing the Joomla email configuration. The correct fix would be to get a certificate in the name of mydomain.com, but this is not available in my hosting environment. Some people have reported to solve it by changing the email send method to PHP Mail or Sendmail, but again, these two were not available in my host service environment, so I had to stick with SMTP and the certificate in the name of kinghost.net.

First you need to know if the problem you are having is the same I had. If you enable the debug messages, do you see the error about the certificate mismatch? If so, you need to find out in the name of what domain the certificate is. In my case, the certificate was in the name of kinghost.net (my hosting service) but the SMTP server I had in the settings was smtp.mydomain.com, thus the mismatch. What I did was to change the SMTP server to smtp.kinghost.net and so no mismatch anymore.

I hope it helps.

Regards,
Fabio.

Hello Fabio,

thank you for your response.
My host gives the opportunity to use a Let's Encrypt certificate, it's a free service so that's great.
I can choose which domain i want to added to the certificate, like mywebsite.com, mail.mywebsite.com, smtp.mywebsite.com
So i tried with and without smtp.mywebsite.com
I tried every mail option in Joomla, sendmail, php mail and smtp. Without error reporting the email test works for all 3. With error reporting i get the same error messages as you and with all 3 email send types, also the escapeshellcmd php extension is mentioned in the error. My host refuses to turn it on because of a bug you can misuse.
Now on the joomla forum it is confirmed that version 3.7.0 will have the latest PHP mailer 5.2.20, where the vulnerable bug is fixed.
See forum.joomla.org/viewtopic.php?f=706&t=947605

So most probably the issue is with the certificate. And the bug is only when using mass mailer from CB, but also Joomla's own.
Not the single registrations emails.

The host is offering a workaround, but they need my admin login for Joomla. I'm not happy with that, there is private info on my site from users.
So i'd like them to tell me what the work around is. I can do it myself.
If it's just setting SMTP, i already tested that.

Thanks for you help so far, i appreciated it.

Hopefully it will be solved soon.

Kind regards,
Jerry

Hi Jerry, if you are familiar with AkeebaBackup you can create a copy of your site in a subdirecotry (make sure you use a separate database) and then delete all users in that copy before you give them access. Then see what they changed and do the same thing in your site in production.

Regards,
Fabio.

Hi Fabio,

great tip!
I will see what they come up with and maybe do as you advised.

Thanks!
Jerry