There will be times (hopefully) you receive a response/return phone call (not just outbound) and you will need to quickly be able to decipher who the lead initially belonged to.

They need to remove their belongings and move out ASAP.

If you go that route, have someone there to remove his belongings for him along with a locksmith to change the locks at the same time. 

@Anthony Catoni @Robert Gaona   I have been stationed in Germany , and belong to he same mastermind group  as Josh. 

Again - wife and I are learning drinking from firehoses.

After one year, a new phase 1 needs to be performed.Many lenders have their own scopes that go beyond the standard phase 1 such as asbestos, LBP, radon and lead in drinking water.

If the account doesn't belong to the landlord, and they're not getting the rent in advance, then is it legal?

Food and drinks provided, must rsvp. 

Here in India at least; most Office building tenants belong to one of 3 categories;1] Long term committed lease with significant security deposits.

Also, you can spell out that you are providing no coverge for their belongings and/or loss of use of the property.Remember, most companies who write Homeowners Insurance will require you to rewrite the policy when the building is no longer owner occupied.