Hi @Evi-Chalk
Thanks for your post. Please allow me to extend you a very warm welcome to the Community Forum. I hope you find it a useful tool.
It was either rejected, or the email address is invalid (incorrect or doesn’t exist). You will get an email explaining the error at the very end of the undeliverable email, the last line with advise the cause of the email delivery failure. could you confirm the exact error message?
Generally speaking when emails bounce back it is because the receiver hasn't whitelisted the MYOB domain: *@apps.myob.com. You would need to make sure that the receiver hasn't marked that domain as spam and that you have the correct email address.
Please let me know if you need further help.
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Cheers,
Leneth