Performance problems.
WHAT CAUSES SLOWNESS
A very large mailbox Very large folders A poor connection A client synchronising everything at once
THE LARGE MAILBOX PROBLEM
Tens of thousands of messages in one folder slows every client.
WHAT TO DO
Archive old mail into dated folders Empty Trash and Spam Delete what you do not need
THE FOLDER SIZE POINT
Many folders with fewer messages each performs better than one enormous inbox.
FOR SLOW INITIAL SYNCHRONISATION
Expected with a large mailbox. It completes eventually.
Limit how much is synchronised locally if it is impractical.
FOR STUCK SENDING
A large attachment, or a connection interruption.
Check the outbox.
FOR CONNECTIONS THAT DROP
Poor connectivity, or too many simultaneous connections from one account.
Reduce how many devices check simultaneously.
WHAT TO CHECK
Mailbox size against your quota.
A mailbox near its limit behaves badly.
