What does everyone use for "evidence of actual receipt" for delivering and wait times for Reg B and TRID?

I am wondering if the following documentation would be acceptable:

lender/borrower conversation comments
email read receipt

Any suggestions or comments would be appreciated!

I don't recommend relying on an email read receipt. A number of email clients don't support them, and many of those that do send a receipt when the email appears in preview mode, before the recipient actually opens the email (if he ever does). For email, I recommend an actual statement (email acceptable) from the addressee. A simple "Got it. Thanks!" will make the grade.

Notes from a conversation (who, what and when) should also make it.