While your "intention" is to not fly more than 50' or not above the trees what happens if you lose orientation, or you experience lose of signal and the Return To Home height is mistakenly set to 150'AGL? What about if you have a Home Point Error (yes rare but possible) and the aircraft suddenly heads to an unknown region without your control?
I handle it by calling them. If no answer I leave a message. If I talk with them I ask them how they would like me to handle in the future and ask if there is an email address I can email my notification to (gives me a paper trail just in case). Either way I document it in my flight logs just in case.
I had a tough time with our local MediVac (heliport only) here at the hospital. They are "coordinated" out of another area and not here at the hospital even though they fly in and out here almost hourly.. I would guess it took me no less than 12 phone calls and I finally got the right phone# via a Facebook friend. I called Flight Watch and arranged a sit down meeting with one of their coordinators. Together we came up with a system of notification that is a 2-way system. She got it approved and now we've been doing it this way for a couple of years (maybe more looking back). We call Flight Watch, give them our flight details (time, location, Max height, estimated flight area, time on scene etc) and they will then let me know if one of their aircraft is "Active" in my area. They take down my name and contact number and if they dispatch one of the aircraft to or over my area they call. At the end of the flight session I call them back and let them know I'm down on the ground.
This has worked splendidly since day one and they have indeed called me a few different times. One time she was actually landing at an accident scene just 1/8 mile from where we were shooting and we landed until she was airborne and back out of the area. Easy Peasy!
Also in an effort for complete transparency last weekend this "system" failed slightly. I made the usual phone call, prepped, inspected and launched my UAS. I was at 150' when my VO announced AIRCRAFT APPROACHING! Sure enough here comes one of the MediVac heli almost directly over head (maybe slight off to my 2 o'clock at 1,000'. No type of incident at all but to know they didn't call or worse yet LET ME KNOW WHILE I WAS ON THE PHONE was disappointing.