Thanks for bringing up this question. You have already made a number of suggestions as to how you can start an email or a letter. I think what phrase to choose depends on the relationship you have with the person you are writing to. If it’s long time friend a less formal start will do. If it’s a potential business partner you should use different words.
I have found that it is always good to open a letter by referring to a previous exchange I had with the person.[YSaerTTEW443543]