What does the phrase letter and in mean?

The phrase "letter and in" doesn't have a standard meaning or common usage in English. It seems like it might be a misspelling or a combination of words that doesn't make sense grammatically.

It's possible you're thinking of one of these phrases:

* "Letter and in" could be a typo for "Letter and in" (meaning a letter that is inside something).

* "Letter and in" could be a typo for "Letter and ink" (referring to writing with ink).

If you can provide more context, I might be able to help decipher what you meant. For example:

* What was the phrase used in relation to?

* Was it a written sentence or a spoken phrase?

* What was the overall topic of the conversation or document?

Please provide more details so I can understand the intended meaning.