Every couple needs to evolve boundaries that work for them in terms of e-mail, PC access, snail mail, financial accounts, going into files or desks, bathroom privacy, etc. The more respectful of privacy, paradoxically, the more trusting the relationship seemed to be.
I arranged for a list of p/w's in a pre-arranged spot should there be an emergency.
The only time I ever had the p/w to someone else's e-mail account was when I set one up for my tech-awkward parents and a former SO.
I have known people who had lived with control-freaks who demanded access to everything. Guess my attitude was shaped as a small kid when my parents respected my privacy and for example never opened my mail, just as I didn't go through their things. (When my folks died it felt very strange to sort through places and things that had been off-limits my whole life.)
If I knew what I were doing, why would I take lessons?
"Things should be as simple as possible, but no simpler." - Einstein
I think it varies for couples but transparent is a big reason especially if there have been issues of infidelity in the relationship or even in one's past. That will make the need for transparency much greater.
Fiance and I know each other's email passwords and we share one. Having access to these things make things easier for each person. We still respect each other's space and half the time I forget his stuff and have to ask him. He is a bad computer security person has like one password for everything. lol
My fiancé and I have been together for 13 years almost and we make a point of keeping access private. Obviously this is absolutely essential if either party accesses work info.
I actually got really angry with him because he posted something innocent to FB on my account and told me about it. Even though I don't bother to log out of FB (or COTH!) on the iPad, I explained - strongly - that this was a violation of my personal space and he must not ever do it again!!
I would give him my PIN for my bank card well before I'd let him trawl thru my email!!
I'm an open book, I'm honest to a fault! I tell my husband *eveything*, and for goodness sakes I'm a "home nudist", so really *nothing* is hidden from him, LOL. Last week I had a hot dream I was cheating on him, and as soon as I woke up I woke him up and told him about it. (I felt guilty )
However my husband is very private, which bothers me only because it's 180 from me. However twice my gut told me check text messages or email, and my gut was right both times. Ex girlfriends had sent nasty pics or texts, and I know he just wanted it to go away and not turn into anything further, so I have now banned two exes from contact with him. (I'm totally cool with exes normally.)
I don't have any of his passwords, if we share an account (ie Netflix, Amazon, etc) then we use an agreed upon password. He doesn't have mine, but we do know eachothers PIN #s.
Not to get in your business but as someone who at one point dated a guy who was extremely private and a few times I inadvertently found inappropriate pics/texts on his cell that he claimed were from ex's and that he wasn't soliciting them in the end it turned out to be furthest from the truth. I naively (he was a bit older) believed him at first and in the end I found out the truth the hard way.
Not to make you paranoid but why would he keep these nasty pics/text if he just wanted it to go away.. Please be careful as someone who as been there before.