Mail no longer opens at start up, missing from HD

I am running 10.6.8 on an iMac and sometime after a recent update- in the last few months- everything that I had set to Open at Start Up stopped doing that. I went to Settings/Accounts/User Info and when I tried to Add Mail to the list of Start Up items, it's nowhere to be found. (Not in Applications Folder, not in Hard Drive as an application..but it is running.. huh?)

I did add Safari back in (it had disappeared too but I found it and put it back)

Any help appreciated.

AKH