I sometimes receive emails from companies selling such lists. But, from what I understand the lists aren't always accurate. If you send to many email correspondence to people that don't want them then they'll mark you as SPAM. This could stop you from sending emails all together.
The best way in my opinion is to just itemize the cities you service and then use your favorite search engine to find the contacts. Also, you can call and build a relationship with one REO specialist and they'll typically have a list already compiled of their colleagues and even if they don't they have access to their MLS's database and can typically export that list into a spreadsheet. Only problem with that is you get the entire list of all realtors not just REO specialist. Typically means you'll have to send out 100+ emails to reach one specialist.
Good luck.