I am not sure I understand the problem correctly. If you enter just a single address, without commas, do you receive emails? If you don't, please let me know how exactly you have scheduled your backup: if by CRON, which cron script you're using, otherwise which method you're using (front-end backup, WebCron.org, custom PHP script, Akeeba Remote CLI, a third party service and which one, ...).
Nicholas K. Dionysopoulos
Lead Developer and Director
π¬π·Greek: native π¬π§English: excellent π«π·French: basic β’ π My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!