You may receive the message "This address is too long. Addresses are a maximum of 16 characters" when you send your email for one of two reasons. After trying the first solution, check to see if you can send your email. If you are still unable to send your email, continue to the next solution.
Separate Each email Address
When you send an email to multiple recipients, you must separate each email address so the AOL mail servers can determine where the email should be delivered.
To separate each email address:
Separate each email address with a comma (,).
Verify the email Addresses Are Valid
If you're sending email to someone's Internet email address, the email domain suffix (e.g., @compuserve.com) must be correctly set up.
To verify all the email addresses are valid:
Check that each email address is typed correctly with no spaces and with the @ symbol in the correct place, for example, firstname.lastname@example.org.
Note: Symbols, such as #, %, or *, are not valid characters in an email address.