Another example is that with a tax auction it is common for all the interested parties to not be notified 100% correctly meaning they could in theory come back later and try to reverse the sale and take the property back!

Send it by US Mail with proof of delivery required and/or place it in an envelope with their name on it and post it on their door. 

The demand letter does not go anywhere except in tenant's junk box or undelivered mail.

For example, if I purchase a site entitled to 100 dwelling units under a newly formed holding company and the only thing linking me to it is a shared PO box mailing address on the holding entity, the lender gets alerted.

In some places there are a few days grace period to allow for rent that is sent via mail (which I don't get because if it is due on the 1st, plan ahead). 

Its pros include streamlined property tracking, access to owner data, automated direct mail campaigns, and team collaboration features.

After inquiring several times if a tax preparer has been assigned, on April 12th I was notified someone was assigned.I was then told an extension will be filed.I asked the tax preparer several times after he was assigned for a status update. 

Once you think there is no law pertaining to the activity then the work begins this is a belly to belly business your not going to do this on E mail and text messaging .. you will need to be able to sit down with these folks or it will never happen.

My LLC is registered obviously, then I received a form in the mail once the property was recorded after purchase. 

Geez...I would notify the (female) tenant that she is in breach of contract.