Hi !
Did you create logs to send your emails?
Does the filter you put in not block incoming emails? (see also your firewall)

Have you checked your email filters? Check the spam folder. Whether your email service is integrated with POP3 or IMAP ? If all is correct, then it is worth checking the module sending code. The most likely problem is the critical mismatch of the script with the main script on the hosting. something similar solved by editing the code from the web development company . At that time it was the only option, but decided quickly,