When the business operates from more than one place.
ADDRESS STRUCTURE
Either one set of role addresses for the whole business, with forwarders routing by location, or location-specific addresses such as lagos@ and abuja@.
One set is simpler for customers. Location-specific addresses help when service genuinely differs by branch.
SHARED ACCESS
IMAP works from anywhere, so a shared mailbox is reachable from every location without special arrangement.
Agree a convention for who handles what, or two branches reply to the same customer.
PRACTICAL POINTS
Standardise the mail client setup across locations, so support is one process rather than several Standardise signatures, with the branch detail as the only variable Keep one list of who holds which address across all locations
CONNECTIVITY
Where one location has a poor connection, webmail is more tolerant than a client synchronising large mailboxes.
FIREWALL BLOCKS
Each location has its own IP address. A block affecting one branch will not affect the others, which is a useful diagnostic: if only one office cannot connect, it is almost certainly a block.