Two years before Twitter landed in 2006, Donald Trump had to resort to pen and paper. Back in those heady days, him and Richard Branson were also reality television rivals.
In the early noughties both businessmen hit our screens in a bid to scour the US for budding entrepreneurs - Trump on The Apprentice and Richard Branson on (the not so catchily titled) The Rebel Billionaire: Branson's Quest for the Best.
Despite the fact Branson's show only lasted for one series, Trump was not about to let a rival go without insulting him.
In a letter recently published in Branson's new autobiography Finding My Virginity, Trump tells Branson to quit television, and his "terrible" business while he is at it.
His "terrible" business didn't stop Trump attending a Virgin launch two years prior in 2002, but the letter certainly sounds like the Trump we know and... Anyway, here it is in full.
...now that I have watched your show, I wish you came to me and asked my advice - I would have told you not to bother.
You have no television persona and, as I found out with others a long time ago, if it's not there there's not a thing in the world you can do about it. At least your dismal ratings can now allow you to concentrate on your airline which, I am sure, needs every ounce of your energy.
It is obviously a terrible business and I can't imagine, with fuel prices etc., that you can be doing any better in it than anyone else.
Like television, you should try to get out the airline business too, as soon as possible!
Actually, I wonder out loud how you can be anywhere close to a billionaire and be in that business.
Perhaps the title of your show, The Rebel Billionaire, is misleading?
In any event, do not use me to promote your rapidly sinking show - you are a big boy, try doing it yourself!
Donald J. Trump
Branson hasn't exactly been shy about his feelings towards Trump in recent years either.
He even published a blog on his own website in the lead up to the 2016 Presidential election telling American citizens not to vote for him.