Posting by email ended with Undelivered Mail Returned to Sender

I wanted to try out posting to my blog by email, but it didn’t actually work. After several retries, my email provider said the email couldn’t be delivered. It identified the error as … “host
mail.writeas.com[50.56.249.138] said: 451 4.3.2 Internal server error (in
reply to RCPT TO command)”

Has anyone else struck this issue? I’ve double-checked the send-to address for the blog and it’s correct.

Thanks, in advance :slight_smile:
John