Hi Barbara,
Currently, those fields are not available for mapping in IOM. You can request that functionality in a future version by submitting to our UserVoice site:
http://iom.uservoice.com/forums/18118-importomatic

Upon further review of your issue, it appears that you cannot globally delete/change this field in RE either. One of our consultants mentioned this scenario as one that she also encountered in her previous nonprofit job and had to manually re-key all the bad entries.

If there are way too many for your taste, we have a development department that could investigate writing a script for you to solve your issue. Contact sales@omaticsoftware.com if that's something you might want to do.

Hope this helps!
Stephanie Johnson

Thanks for the answer, Stephanie. I think we'll just ignore the field for now, and when I feel like mindless task work, I'll tackle the 2500 we have!