In my first month since becoming interested, I have setup my phone, website, DBA(waiting till first deal to get LLC), pulled leads for absentee owners/recent cash buyers and began my mailing campaigns as well as set out bandit signs.

In my first month since becoming interested, I have setup my phone, website, DBA(waiting till first deal to get LLC), pulled leads for absentee owners/recent cash buyers and began my buyer/seller mailing campaigns as well as set out bandit signs.!!!

I'm not sure how to find out which mail carrier to speak to, but I'd love a shot at that. 

Im about to start another direct mail campaign and I'm wondering what is the best type of mailing to get the most motivated seller leads.

Probably yours - but I would cover my butt with a certified letter mailed to the prior owner and wholesaler both with a reasonable time limit.

I know on their side, there is the risk that someone could be wasting their time.Is it better for someone in my position to stick to driving for dollars, FSBO, direct mailing, etc. to have that direct contact and get more walkthroughs?

Normally they just mail the release.

Take them to court , send any mail to the address of the rental , they will be getting their mail  sent to them

Worst case scenario you can pay a VA to scrub the list and convert it into spreadsheet or CSV that you can mail directly from.  

. :-) Yes, repairs and maintenance can be hassle free, until you have to gently remind the landlord about the maintenance request you made x days/weeks ago.