Reading your mail offline when using IMAP

How to read messages that live on the server when you have no connection.

IMAP keeps your mail on the server, and your mail program downloads messages as you open them. Without a connection, anything it has not already downloaded is unavailable. Synchronising avoids this by keeping a local copy of the folders you choose.

Choosing what to synchronise

Most mail programs synchronise the Inbox and leave your other folders alone. Open the account's folder or synchronisation settings, then select every folder you want available offline.

If a folder you created on another device is missing from that list, refresh the folder list first. Mail programs cache the list, so a folder made elsewhere may not appear until you do.

Synchronising before you disconnect

Run a synchronisation while you still have a connection. The first one can take a while when your folders hold large messages, because the program downloads everything you selected. After that it only fetches what has changed.

Mail programs on phones and laptops now synchronise continuously in the background. In practice this means leaving the program open and connected for long enough to finish before you travel.