From my 6 years of living in USA, my observation, I have realized that in American norms, parents' well-being in not their kids' responsibility.

(There are other ways to obtain/develop that evidence - such as using certified mail or my “practical advice” below.)In your case, because your friend found the letter inside the mailbox of the last known address, you now have specific evidence of having mailed the letter “…by first class mail, to the tenant's last known place of residence” - “Unless other arrangements (had been) made in writing by the tenant…”Again, in my (non-lawyer) opinion, you’ve complied with the letter of the law as to your concern - “Unless other arrangements (had been) made in writing by the tenant…”[Practical advice: Where I self-manage, in my “Notices” section of the lease, besides my physical address, phone numbers, etc for notices to me, I provide two email addresses for myself, and state in that part that email is my preferred method of communication.

He has had a physical altercation with the boyfriend of this couple.

After an intro call and vision board, intro to strategic lending partner, four physical tours, two offers on two properties (with the second accepted below asking price) a quick inspection with (minor inspection issues resolved by seller), appraisal waiver and below market rate lock..

Given how badly Airbnb has managed owner relations, we have made a hard pivot to adding as wide a distribution net as physically possible.

Does this mean that we will just pay less at closing and not get the physical security deposits?

If its not being reported to the bureaus then the only thing you have to concern yourself with is (As Jay points out) any potential deficiency you may be on the hook for. the actual physical processing of a DIL is very similar to a foreclosure in that there is title work, recording of documents, etc.

Pick up an algebra or quantum physics book if you know nothing about algebra or quantum physics and let me know how long it takes you to figure out algebra or quatum physics on your own.

Physical labor, computer labor, tutoring... anything within reason.

Tenant friendly state shouldn’t be a concern IMO, just screen tenants well, be professional and buy in a good location and you probably won’t ever have to deal with the courts.