Two months have gone by (with late rent being on the 3rd) and I didn't receive any kind of notification other than this stinky letter today the 15th saying I have 3 days to pay the two months rent and soon to come next month.

then you can get a proof of funds letter to go shopping.  

This is not the same process as a SFR purchase, where the buyer obtains a letter of qualification from a dubious mortgage broker; this is a very intensive evaluation.That being said, nothing is to stop any interested party, qualified or not from making an unsolicited offer.  

I plan on sending a letter to the address stating my interest of a potential deal. 

@Brian Jordan, it's a sad world where Sellers will let a lot of their property equity be frittered away by your promise of quick cash, even though you've told them in bold letters that you intend on making a HUGE PROFIT out of them, rather than sensibly request that you (having told them that you're also a Licensed Realtor) list it for them for normal commission only!

Send them a letter (not yellow letter because they are getting dozens of them) telling them you found their house to be apparently vacant.

Send them a letter (not yellow letter because they are getting dozens of them) telling them you found their house to be apparently vacant.

Ok Stephen heres the deal i have to do the repairs and the payments are 1500 a month right now there are 2 apartment rented the first floor has to be done over complete to make it an apartment the two rents equal the 1500 the new apartment would bring in 1300 a month taxes are 5500 water an sewer are 1050 ins 2400 snow removal 500a year put  away 500a ayear for repairs the 1500 goes towards the principle theres no interest and the balloon payment in 5 years

Is my only option sending a letter and hoping they respond?

I did notice that the post said most portfolio loans have a higher interest rate typically than what you'd get with a conventional lender, and that they are usually shorter in term or have a balloon payment.Based on my personal situation, I shouldn't have much of an issue getting conventional financing for the first few properties.