I’d not worry about her mail over the next few days. Nor worry about the business matters either. Deal with those items next week. Your mind is looking for, and will seek, things that you “need” to do in order to justify contacting her. Let it go.
This is not to be mean to her. It is for you to prove, to yourself, you can do it. And will do it!
Do whatever you’d have been doing if she wasn’t in town.
As for the pile of mail. She moved out. Right? It’s up to her to change her mailing address with her various business and personal contacts.
If you’ve never discussed anything regarding her mail or address, then next week I’d let her know you received some mail for her and she needs to change her address. This is not a new concept to her. She’s made several trips to pick up items and even a car. If you’ve discussed the mail before, just drop the mail back at the post office and tell them that this person doesn’t live here anymore.
