Thank you for the answer Rapunzl.

Well, that might be the issue:

The website is hosted in iceland but I am using a domain name from a provider in France to forward to the site.

In the Joomla configuration I use the mail parameters from the French provider (SMTP with authentication).

In the CB configuration I put the "from" and "reply-to" addresses from the French provider also

Using the French provider SMTP works for mass email but not for CB.

Would that be the reason?

Is there a specific parameter to change I could point out to the Icelandic host so that emails go through? In other words, what would be the typical obstacles that I could ask them to check?

Thanks a lot for your help. It is incredibly valuable.

Thanks a lot for the very prompt answer Nant.

I have tried both the atuhentication off and the phpmailer.

I register a dummy account and get no error message:

"Your registration requires email confirmation and approval. Please follow the confirmation steps sent to you in email. Once approved you will be sent an acceptance notice to the e-mail address you entered.

When you receive approval then you will be able to log in."

But neither the admin or the dummy email received the message.

I had done several tests and sendmail and phpmailer did not work (They also don't work for mass email), which is why I switched to SMTP (with the fallback I guess). SMTP worked like a charm for the mass email (with authentication) but not for CB

I guess that points out to some kind of block at my host in Iceland. I am not too sure what it could be.

Do you know if there is a way to figure out what the blocking could be from the system info in the backend?

Thanks again very much for your help