I was working a good client yesterday for a different problem when we tried also to figure out why they couldn’t send email over POP or IMAP from outlook through GoDaddy hosted email for their domain.
They could receive email just fine but 99 times out of 100 they couldn’t send email and would get a 552 error “Message rejected for spam or virus content”. GoDaddy puts the blame on the person’s machine/network/router. The problem here is that even with a different machine on a different network the same error occurs.
This is a widespread problem for MANY users and it is caused by GoDaddy flagging your domain/email as spam. But overall they do not seem to care or want to fix it. POP and IMAP work fine from her iPhone … just not outlook.
This problem is not also inherent to Outlook. Others report problems with other mail clients as well.
See these posts and frustration of their customers
What should you do?