Throw-away e-mail addresses

We have accounts with all the webmail providers for deliverability testing.

Today I tried to set up the main contact address for my Yahoo! account to be:
yahoo-throw@example.com, the attempt was blocked by Yahoo! with an error. Oops! There's a problem. (#604,E2) You are trying to add an email address that has been blocked by the email address owner.
Please enter a different email address.
This is not true as Yahoo! had not tested this address, no connection came from their servers.

I could add these addresses however: yoo-throw@example.com & yaho-throw@example.com, so our tentative conclusion is that Yahoo! are filtering attempts to use throw-away address as a contact point.

Clients will need to be a little creative when using throw-away addresses with these and similar services if bogus error messages are to be avoided.

Throw-away e-mail addresses are provided as part of the SMTP service to our clients.