Email Problems?

Hi, I am using a macintosh, OS 9.2.2, Outlook Express 5.06 (using pop3.)

On one of my accounts…(Mail Server Murdock) I am getting duplicate emails, just started today…and I just saw an email come in, then it magically disappeared, I contacted my client, who has resent the email…and then mentioned a few that he sent that I didn’t get. Is it my macintosh, or should I send DH a Support Request…I don’t want to inundate DH support if it is already a known issue…?