OK, After posting I realise there are a few things i got wrong, but i can't go back and edit it now. - I'll post another version later.

BTW, testing, I have come across this, yahoou.com lists one MX, priority 0 MX=> '.' ??

Hi Folks, I have done a little on the class SMTP_validateEmail this morning, as it is something I have been meaning to implement for a few months. - nice work so far, thanks.

Basically, I would like to get a confirmed "NO" if the email address is 553, like when Joe Public typoes his address in as [email]jowpublic@domain.com[/email] on my site, and a confimed "YES" if I can get at least a postive 25x or 45x from the MX. In all other cases, what I am going to do is remind the user that I was unable to verify the address and ask them to look at it twice for typos before finally hitting submit.

So, as you can see, I have moved away from just returning true/false, to also returning some text strings to check for. This could maybe be done in a better way.

I have also added a nasty hack to work on windoze without NET_DNS, the ability to set nameservers when initialising the class and I have added to, and formatted the debug output a little. There's also a few other little changes in there as you can see.

Thanks again.