How to approach owner of two off-market adjacent buildings?

[Aaron K.]

I own a 7-unit apartment building, and attached to my building are two un-occupied buildings of similar size.  Both buildings have been abandoned for some time, but still look OK from the outside.  I found the LLC name and registered address of the two buildings, they're both owned by the same LLC.  What's the best way to contact and approach the owner about a possible sale?  Hard to present an offer without seeing the inside, but I'd like to at least get a dialogue going, see if they might be interested in selling.  I have only a mailing address - no phone or email.  Do I just mail a personal letter, or is there a better way to do it?