I've pasted Godaddy's response below.
Apparently they have intentionally blocked all outgoing email to any @yahoo, @gmail or @aol email address.
This is interesting because email has worked on another godaddy-hosted website of mine for many months to these addresses and I don't recall getting any notification that they were going to start blocking anything.

Anyway, here's their response (below) - I hope to go through the setup this evening to see if I can make it work.



That error message indicates you are trying to send to a @yahoo, @gmail or @aol email address. Unfortunately our relay server blocks emails from going to those specific addresses. Sorry for any inconvenience this may have caused. You can create a forwarding email account so you can still receive those emails if you would like.

To setup an email forwarding account, please use the following instructions:

First, log into your account:

• Go to the Go Daddy Account Login Page
• Log in using your account username (which may be the same as your customer number) and password

If you have trouble logging in, our password reset form may help you. You can find this form through the following link:
Account Retrieval Page

Once logged in, follow these steps:


1. Select 'Email' option from the 'My Products' menu. (If this option is not available you will need to select 'Free Products List').
2. Click on the 'Email Forwarding Accounts' link.
3. Click on the 'Use Credit' link if you are using a free credit, or the "Manage Account" link otherwise.
4. If using a credit, Make the domain choice on the right hand side, and click the "Continue" button.
5. If using a credit, Now you can click the "Manage Account" link next to the email account.
6. Click "Forwarding Plans"
7. Click the orange "Add" button to the right, next to the email account to setup.
8. Enter the first part of the email address that you are planning to create.
9. Choose the domain you wish to use from the dropdown list.
10. Enter the email address you would like all mail forwarded to in the 'Redirect Mail To' field.*
11 Select 'Yes' if you would like this account to be a catch-all account.
12. Select 'Yes' if you would like this account to have an auto-responder.
13. Click 'Save Settings' at the bottom.

*All messages sent to this address will then be forwarded on to the address you specify automatically.

My problem (sending verification emails to new registrants from my Godaddy-hosted Forum) disappeared but the root cause is still unknown - I suspect something may have gone awry with Godaddy's email address blocking scheme.

I did get another clarification from Godaddy tech support...

Any email generated from a Godaddy server cannot specify @yahoo.com, @gmail.com, or @aol.com as a FROM address. They are undoubtedly doing this to prevent spoofing which is understandable and perfectly OK with me. However, this was not the issue in my case as I was using a godaddy email address (associated with my site's domain) as the FROM address.

Still, other YAF deployments might run into this issue, so...
If you are running YAF through a Godaddy-hosted site, make sure that the forum email address is set to a non-blocked domain; e.g. admin@yourgodaddyhosteddomain.whatever. Do not use a yahoo, gmail, or aol email account as your forum's administrative email address.

Again, this was not the issue for me but the problem did mysteriously clear up after logging a case with Godaddy support .

I have made no changes to my YAF setup and verification emails for new registrants are now working perfectly.