Mail: Mailbox Behavior When Switching Mail Providers: What to expect?

Hello Community,

I am considering switching my email provider to a new company. While I'm crystal clear on how to handle the DNS settings, I'm a bit unclear on what I can expect with the various mailbox accounts that are (and have been) in place for years.

These are POP email accounts, not IMAP.

Can I simply go into settings and change the Server Settings to align with my new service provider and have all material in that mailbox remain intact? or will I need to export the mailbox and import after the fact.

For extra credit :)

Through the old service provider there are 4 accounts set up:

snap@cereal.com

crackle@cereal.com

pop@cereal.com

wheaties@cereal.com

In the MailApp all 4 have their own mailboxes and about a years worth of sent and received emails for each that need to remain after the switch (remember these are POP accounts not IMAP).

At the new service provider I'm going with three accounts snap@, crackle@ and pop@ BUT wheaties@ will be set up as an alias to snap@ so it will share the mailbox.

Can I import the years worth of wheaties@ inbox and sent into the snap@ inbox and sent then delete the wheaties@ account or will this create issues.

Thank you in advance for any wisdom