Let's break it down:
* "After I have received" is a grammatically correct phrase that means "once I have gotten something." It's used to express a sequence of events, where one thing happens after another.
* Example: "After I have received your payment, I will ship your order."
* "Just in expression answer after letter" is not a grammatically correct phrase and doesn't make sense.
It's likely you are trying to express something related to receiving a letter and then providing an answer.
Here are some more accurate ways to express that:
* "I will respond to the letter after I have received it." This clearly indicates the order of events.
* "Upon receipt of the letter, I will provide an answer." This is a more formal way to say the same thing.
* "Please let me know once you have received the letter and I will provide a response." This adds a bit of politeness and ensures clear communication.
Make sure you use complete and grammatically correct sentences to ensure your meaning is clear!