I've changed the code but now I discovered the following in the error_log for Apache:
DBD::mysql::st execute failed: You have an error in your SQL syntax near 'agostino@mycomcast.com,karen@adkinsrealty.com,nmanning@realtor.com,team1@atlanti' at line 1

I should try $dbh->quote() then, right? Cause now it seems like another issue with the actual data I'm sending to MySQL.

Thanks,
Ralph