phrase request

They seem okay, but there are better options. For 4, I prefer for him instead of from him since for is used when you do something on someone else’s behalf.

Anyway, two more idiomatic phrases, in my opinion, are

1. A sends his regards.
   Example: I met A recently and he sends his regards.
2. A says hello.
   Example: I met A recently and he says hello.

1 sound more formal. 2 is casual. As J.R. points out, 1 could be too formal for some everyday conversations. Considering your situation, I think they are both possible. If you want to sound more casual or friendly, use 2.

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