I haven't seen him
means, essentially, I have not seen him recently.
I didn't see him
means, I did not see him at some particular time.
When the "particular time" is recently, the two can be used almost interchangeably:
"Have you seen Bob around?"
"No, I haven't seen him."
"Did you see Bob just walk by here?"
"No, I didn't see him."
Other times, though, there are clearer dividing lines between when to use didn't see instead of haven't seen:
"Have you seen Mr. Hernandez go into Mrs. Olson's house?"
"Yes, I have seen that many times."
"On the night of the murder, did you see Mr. Hernandez go into Mrs. Olson's house?"
"Yes, I did see that."
The first question refers to a more open-ended span of time, while the second refers to a very specific time segment.
You could say either one, though there is some difference between them.
I haven't slept well.
This does not indicate any timeframe. It is possible you did not sleep well for a day, week, month, etc.
I didn't sleep well yesterday.
Here we know it was only one day (yesterday).
Best Answer
Present Perfect and Past Simple are two concurent tenses. They often are interchangeable, especially in American English. So you can say either:
or
Note that "I didn't received your email" is not correct because you cannot use -ed form of the main verb since you already have the verb "didn't".