Verify an e-mail-adress - syntax and dns

[Ingo Linkweiler]

Bjoern Schliessmann schrieb:
> Ingo Linkweiler wrote:
> 
>> b) verify an existing mailserver or DNS/MX records
> 
> "Or"? That's two different things.
> 
> If you don't know already: Even if you test all this, it is still
> possible that
> 
> - the target mail account doesn't exist
> - the sender's IP is filtered by the server so he'll reject

Yes, I know this.
But its still better than not checking it.
The script will be used as part auf a user registration page to avoid 
dummy-inputs like "jsfhsadgfa at hdhjdfhjh.net"