Email plugin throwing SMTP error code 554

[eluser]taewoo[/eluser]
[quote author="Ahmed Nuaman" date="1201365626"]Does the recipient exist? What normally happens with most SMTP server is that they check who the email's going to and instead of sending it and having an email pop back saying "no-one's here", they do a check to see if this email exists.
[/quote]

Yeap. It exists alright.