Today i was testing SMTP for my email.
I decided to restrict my incoming email from my server and only allowed outgoing/send emails.
i test sending email from my server to other address and it does send email without any issue.
Only issue happened when i placed an order i got error in my log
To be sure i unrestricted the mail setting and was able to send order related email.[05-Jul-2022 03:46:15 UTC] PHP Fatal error: Uncaught Exception: Error: RCPT TO not accepted from server! in /home/xyz/public_html/system/library/mail/smtp.php:259