phpmailer - The following SMTP Error: Data not accepted

Question

I\'m trying to figure out this issue for 6 hours. But there is nothing to make sense. Here is the scenario; There is a well formatted HTML template.

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Answer 1

If you are using the Office 365 SMTP gateway then "SMTP Error: data not accepted." is the response you will get if the mailbox is full (even if you are just sending from it).

Try deleting some messages out of the mailbox.