Dear Bertie and Raymott,
I would just like to mention that it is a consolation (in lack of a better word) for me to see that even sophisticated, native English speakers can have different opinions about the use of Past Perfect.

You can well imagine how difficult it can be for other speakers whose native language has only three tenses, such as present, past and future. ;-)
There is absolutely no need for the past perfect in a sentence that reads "Before I did A, I did B".
"Before I did A, I had done B" This is pointless. You'd need a good reason to say that.
This was one of the first questions
I asked here, and thanks to your enlightening answer :up: , I wouldn't want to say "I had known her before I met you" anymore.

However, I kind of feel that Bertietheblue's example ('Before I replied to the email, I checked [that I knew] who'd sent it to me.') is not as straightforward as mine was. Why? Because we have to deal with a third action that had already happened even before I checked my email. It's
not the case "Before I replied to the email, I had :cross: checked...." (which is deemed to be wrong), but before all of this (and "before" is not written here) someone had sent me an email.
Do I make sense, or am I wrong?

Thank you in advance for your answer. :up: