What I'd do is send them a letter with delivery confirmation, saying that you have relied upon their written notice to move out July 31st via text message, and just want to be sure they understand that if they are in the unit past July 31st, they will be a holdover tenant and you will have to evict them if they are still in the unit past that date.  

Simple.Send your notices to the address with delivery confirmation and post them on the door.It's not your job to figure out why you don't have your rent.  

Thus:Landlord and Tenants agree to the following changes and/or additions to the Agreement:Effective April 1st, 2016, rent will be increased from $1695 per month to $1779 per month.Landlord signature: _________________________________ Date: __________________This notice was served by the landlord by personal delivery to the tenants on 2/17/2016.Notice to inherited tenants after acquiring new rental property:Notice of Change in Terms of TenancyThis is an Amendment to the rental agreement dated February 21, 2016 (“the Agreement”) between [your name] (“Landlord” or “We”) and [tenants' names] (“Tenants” or “you”) regarding the property located at [address] (“the Premises”).As you may know, your rent has been far below market rate for the past 4 years, without any increases during that time.

Put that in writing, and mail it to him with delivery confirmation, and you could always email it, too.  

There is no requirement that I be at the beck and call of the mail delivery and then forced to rush to the bank so that my tenant can pay via check.

I'd never want to cross any legal boundaries.I'm not certain as to what the exact legal definition of occupancy is in terms of tenancy, but from my point of view, an occupancy would be something that included a leasing contract, payment of utilities, delivery of mail, tenant implements their own furnishings, etc.

They give you a real street address and will accept packages and deliveries that require signatures.I also have a google voice number and gmail account. 

Mail it with delivery confirmation and go post it on the door with a witness or hand it to whoever answers the door.Immediately, give the subletting roommate a 30 day notice to terminate.  

The new tenant paid me monthly installments on that oil bill until it was paid off and ran low enough for them to start calling for deliveries on their own.

Same for paper delivery, UPS, FEDEX?