Error Message while Bulk Uploading
It is possible that an error in an individual email address can cause this error message. This message is generated when certain kinds of errors are present that makes Moodle consider the address not an address.
For example an address like...
jsmith@shaw,ca or jsmith@shaw/ca
Are not considered email address because of the use of a comma or forward slash....
Moodle will not find an error in email addresses that don't exist but still conform to proper email structure
For example an address like....
email@example.com or firstname.lastname@example.org
are likely typing errors and incorrect emails but Moodle will let them be uploaded. They will then create an error message for the Site Administrator and due to the quantity of these errors they will be deleted without notification.
TAKING TIME TO ENSURE THAT YOUR DATA (EMAIL ADDRESSES) IS AS ACCURATE AS POSSIBLE IS A GOOD THING.