Would it bother you if your spouse or s/o opened up your snail mail?
Also, are you the type that would open up your spouse's or s/o's mail?
There was never a problem with doing so if it was a bill or something. But if it was something like an obvious birthday card or a letter from her family, I wouldn't.
If the mail was addressed to the both of you, would you go ahead and open it, or would you just go ahead and let them have at it?
I had to reread this question three times to make sure I got it right as it appeared to be quite irrelevant, but maybe I was missing something. I did, indeed, read it correctly the first time.
If the mail was addressed to someone else, like a neighbor, and the postal worker accidently delivered it to your house, would you open it? Also, would you walk it over to your neighbor?
No, I wouldn't intentionally open it. If it is nearby like across the street or next door, I put it in their mail box or deliver it. If it is on another street, I just leave it in the mailbox and put the flag up.