We usually begin our letters with a greeting like:
1. Dear John, hello,
2. Dear John, salaam,
Should I capitalize h and s in "hello" and "salaam" or not?
Thanks,
ata
In written English, we would not use both "Dear John" and "Hello" as the greeting. You will choose between the two, depending on the situation.
Dear John
How are you? I am well and I am looking forward to seeing you on Saturday.
OR
Hello John
How are you? Etc etc ...
If you really wanted to say "Hello" in the main body of your letter, it would be capitalised because it would form the first word of the first paragraph of your letter, after the greeting. So it would look like:
Dear John
Hello. How are you? Etc etc ...
Please note that I don't like this construction at all.