1. Do not write "the same" in an official email - it makes little sense to them.
Example - I will try to organize the project artifacts and inform you of the same when it is done

This is somewhat an Indian construct. It is better written simply as:
I will try to organize the project artifacts and inform you when that is done


2. Do not write or say, "I have some doubts on this issue"
The term "Doubt" is used in the sense of doubting someone - we use this term because in Indian languages , the word for a "doubt" and a "question" is the same.
The correct usage (for clients) is:
I have a few questions on this issue

3. The term "regard" is not used much in American English. They usually do not say "regarding this issue" or "with regard to this".
Simply use, "about this issue".

4. Do not say "Pardon" when you want someone to repeat what they said. The word "Pardon" is unusual for them and is somewhat formal.

5. Americans do not understand most of the Indian accent immediately - They only understand 75% of what we speak and then interpret the rest. Therefore try not to use shortcut terms such as "Can't" or "Don't". Use the expanded "Cannot" or "Do not".

6. Do not use the term "screwed up" liberally. If a situation is not good, it is better to say, "The situation is messed up". Do not use words such as "shucks", or "pissed off".