https://www.whitehouse.gov/contact/
As stated; heres the link to White House's official "contact us" form.
I've written President Trump numerous times, especially lately.
It's a fact that all presidents periodically see at least SOME of these random letters from the public, so there is a chance he will see what you write.
At the very, very least, I'd imagine they tabulate these as "positive / negative" and track input from the public, for obvious reasons; gauge public support, etc.
So at the very least, I can brighten an intern's day and get placed into that "positive feedback" column. LOL.
But seriously.....WRITE OUR PRESIDENT, PRAY FOR OUR PRESIDENT AND COUNTRY, PRAY FOR YOUR FELLOW ANONS!!!
NOW MORE THAN EVER!!!!
WWG1WGA
MY MESSAGE TO POTUS: WE LOVE YOU MR. PRESIDENT! WE PRAY FOR YOU AND YOUR FAMILY, OUR COUNTRY AND THE MILLIONS OF YOUR SUPPORTERS DURING SUCH AN IMPORTANT TIME IN OUR COUNTRY'S HISTORY. MAY GOD GIVE TO THE STRENGTH AND WISDOM TO DEFEAT THIS EVIL ONCE AND FOR ALL! I PRAY THAT OUR GOD SURROUND YOU WITH HIS GREATEST WARRING ANGELS TO DEFEND AGAINST THE WILES OF THE DEVIL, AND TO KEEP YOU SAFE FROM ALL HARM. I PRAY THE HOLY SPIRIT CONVICT THE MEN AND WOMEN AROUND YOU MR. PRESIDENT TO HAVE COURAGE AND FAITH TO FACE THIS ENEMY AND STAND UNITED IN THE DETERMINATION TO WIN, AND TO CRUSH THE ENEMY AT THIS MOST NEEDED TIME. THANK YOU MR. PRESIDENT FOR TAKING THIS TASK. I HOPE THROUGH ALL THESE TRIALS AND TRIBULATIONS THAT YOU SIR COME AWAY FROM THIS A BETTER, STRONGER, AND MORE GODLY MAN, BETTER TO SERVE AT THE WILL AND PLEASURE OF OUR MIGHTY GOD! YOU SIR ARE ON THE RIGHT SIDE OF HISTORY! YOU HAVE THE LOVE AND SUPPORT OF THE NATION. STAY VIGILANT AND STEADFAST. WE WILL WIN. GOD BLESS YOU AND GOD BLESS THE UNITED STATES.