Mac - email disappearing from Comcast after routing to Apple email

I have iMac desktop with OS X (10.6.8) - I use Comcast as my primary email, but route them to my Apple email. My Comcast email history is disappearing after about 2 weeks. My Apple settings show "Remove copy from server after retrieving message" = 1 week. I thought maybe this means emails will be deleted from Comcast server after 1 week? I went to adjust, but no option for "Never"? I called Comcast, but they say it's not them, so thinking it might be my Apple email settings. My Comcast settings are set to never delete emails in my Inbox.

-Thanks!!!