How do I fix incoming emails going to Trash folder on Mac?

I need some help. My wife tells me a friend sent her an email and she doesn’t find it in her inbox. I tell her to do a search, which she does and it shows up in trash. I laugh tell her she must have deleted it. She gets angry at me for suggesting she’d delete it (and not remember doing so). She yells that I’m (me) the tech person and when she asks for help, I laugh at her. (We’ve been married for 52 years ;-)

Is there an action that can be set for specific incoming emails…like move to trash? And maybe this somehow was mysteriously set?

(i’d like to stretch the 52 years out a bit more)

Thanks in advance

[Re-Titled by Moderator]

Original Title: emails keep going into trasha