Formal:
* Liewe vriend, ek hoop jy vaar goed. (This is the most formal way to say it)
Informal:
* My vriend, ek hoop jy's goed. (This is a more informal way to say it)
* Vriend, hoe gaan dit met jou? (This is a casual way to ask how your friend is doing)
More affectionate:
* Liefste vriend, ek hoop jy het dit goed. (This expresses more affection)
You can also add a personal touch by mentioning something specific about your friend or your shared experience in Africa, making the message more meaningful.