Hi, thank you guys for your responses!
I went to Verizon and found out what it actually was - called MobileEmail, it's a verizon application that can only be downloaded and installed from a Verizon phone by going to start.vzw.com (then downloading it under "Email"). I had it built in when I bought the Omnia and found it more user-friendly than the messaging one (or Outlook). But after I installed the new ROM, all Verizon apps were gone and I can't access the vzw page anymore.
I tried FlexiMail. It looks nice but the major problem I have with it is that it doesn't show me my personal folders. I created about 10 of them in my yahoo account, but FlexiMail only shows the "local" ones: inbox, outbox, etc...
Oh, also, it doesn't notify me about new emails until I actually start the program. That doesn't seem to be very convenient...
I'm still looking for another AP. I wish I could install MobileEmail back on my phone... If anyone could post a .cab file - I'd really appreciate it! I can't access it from my phone...