Not in most states.
can a landlord change the locks on a commercial building without notice
No, a landlord cannot change the locks for abandonment if the tenant has not moved out of the rental property. Changing locks without proper legal process could be considered an illegal eviction and may expose the landlord to legal consequences.
I can only answer for Massachusetts, but I think you can. The landlord has a right of entry, but he should get the permission of tenant, and the tenant has a right to be there at the time. If the landlord needs to get in during an emergency, perhaps he should be calling the police.
You need to check with the landlord about that. You cant just change the locks on a property that you do not own.
Not in any state I know of.
A landlord could get in trouble with the husband for changing the locks, but that seems unlikely, especially with a letter from the wife asking that they be changed. There is also no reason why the wife cannot change the locks herself.
AnswerYou should check your lease. In addition, generally a landlord has the right of access in an emergency. You need to check your local landlord/tenant laws.
Yes. The building belongs to the landlord and needs the key in case of an emergency, or if a tenant abandons the property. Also, you should probably check with the landlord prior to changing locks. There might be a clause in the lease stating that only the landlord can change a lock, not the tenant.
Not in most U.S. states.
Not necessarily. A landlord must have locks installed which must secure your rental dwelling. They don't have to be deadbolt.
If the space is being leased and the tenant is current they really have no business doing so. They have the right to, but as long as they give the tenant a copy of the key they can do what they want. It is their property.
Not in any state that I know of. Most state codes require that the landlord provide a mailbox, and locking it would be a breach of quiet enjoyment.