Why are contacts with ".invalid" appended to their email address not receiving emails?

Environment

Clone sites (including test sites) all versions

Issue

When a clone site is created, all email addresses are appended with a string such as ".invalid" to prevent unwanted messages from being sent.  For example, imagine that the original (i.e. production) site had a scheduled mailing with 1000 recipients.  Without appending email addresses with such a string, this scheduled mailing could be sent from a clone site, in addition to the mailing from the production site.

Resolution

If you wish to send email to a contact record which has the "invalid" or other "make safe" string added to the address field, simply remove the extraneous string from the email address field of the contact record.  You may wish to verify that the disable flag is not set on the contact record as well.  The disable flag is not visible in the default contact workspace, so it will need to be added.  Here is the procedure for editing a contact's email address:

1.  Open the contact record

2.  Find the email field

3.  Edit the field to remove the appended string

4.  Click "save" in the ribbon