I ran into an issue this week with a site I have hosted at NameCheap.com on their shared hosting plans.
NameCheap.com has seen it fit to:
“disabled sending any emails with the field ‘FROM’ containing[an] email address on the domain that does not exist on the server.”
They go on to say that:
“We have taken these measures due to mass SPAM sending through forums, guestbooks, contact forms scripts on our servers.”
This is a bit of a pain if you are using Google Apps or some other remote provider for email. Hopefully, the following will allow you to setup workable SMTP sending from your account, even though your mail is remotely hosted.
Setup a New Subdomain in CPanel
Firstly, you will need to setup a new subdomain in CPanel. If your DNS is running at NameCheap.com this is OK as the entry in CPanel will be automatically setup. If you are running DNS elsewhere, such as GoDaddy.com using the Total DNS tool, you do not actually need to setup a new A Record or CNAME for this. This is really just a dummy subdomain needed to send the mail.
Enter the name of the new subdomain:
Add MX Data for the new Subdomain
Select the new subdomain:
Add the new MX Record, pointing it to your main domain. This will be the main domain in your CPanel account.
This is all you need to do. You can now send out email from your Shared Hosting account using an address that is hosted with a remote email service, such as Google Apps or GoDaddy.com
At this point, you could also create an account locally in under the new subdomain so you can authenticate for SMTP, but I have not seen this to make a difference.