A few decisions made early save a lot of reorganising later.
DECIDE THE FORMAT FIRST
firstname@, or firstname.lastname@, or initial.lastname@. Pick one and apply it to everyone. Consistency means colleagues and customers can guess an address correctly.
ROLE ADDRESSES ALONGSIDE PERSONAL ONES
Create sales@, support@ and accounts@ as well, forwarding to whoever handles them now. When responsibilities move, you change the forwarder rather than telling everyone a new address.
QUOTAS
Give everyone the same sensible quota. Raise individuals who genuinely need more rather than setting everyone unlimited.
PASSWORDS
Generate a strong password for each and require the person to change it on first login. Never use one shared password across mailboxes, and never a pattern like Name2026 that anyone can guess.
SHARED MAILBOXES
Where several people handle one address, either use IMAP so everyone sees the same folders, or use a forwarder to individuals and agree who replies. Both work; decide which, because assuming is how customers get two replies or none.
DOCUMENT IT
Keep a list of who has which address, somewhere other than the mail server.