POP account sending blank email to itself

[Lary]

I have Outlook 2003 with 5 POP accounts. One specific account will randomly
send to itself or creates a blank email in the inbox. I don’t know if it
truly sends an email, because there is no send email in the Sent box of
Outlook. I have rules set for each account to move email from the accounts to
specific folders. I recheck the setup and rules; ran a virus scan and adware
program. Everything appears fine.

Any ideas?

Thanks in advance