"in my previous email" vs "on my previous email"

Question

"In my previous email" references information included in a prior message.

Last Updated: March 20, 2019

"In my previous email" calls attention to the content of your last message.

Explanation provided by a TextRanch English expert

Some examples from our editors:

In my previous email, I mentioned that we will be hosting guests from the Singapore office. Let me tell you more about their upcoming visit.
In my previous email, I wrote that the meeting was on Tuesday, but that was incorrect. The meeting is actually on Wednesday.
In my previous email, I told the first part of my story. I'll continue it here.

Some alternatives from our editors:

In this phrase, the preposition is incorrect. Use "in my previous email" instead of "on my previous email."

Explanation provided by a TextRanch English expert

Some alternatives from our editors:

Answer 1

in my previous email

This is correct

Answer 2

This is not correct. Don't use this phrase.