Always show the list of cached IMAP folders on start
When I start Evolution in offline mode, it displays the cached list of imap-folders. I have configured Evolution to download any email from the server. Whenever I start Evolution I want to be able immediately to reply on emails received in the past.
When I start Evolution in online mode, it sometimes does not display immediately the list of folders. Therefore I cannot access the downloaded messages and reply to them. This happens particularly on transient (network) errors on calling the folders from the server. While any other transient error does not prevent me from using Evolution for emails, (very much) delayed IMAP LSUB answers do block me.
However, if I first start in offline mode and immediately afterwards switch to online mode, (very much) delayed LSUB answers have no impact on the usage.
To demonstrate I setup an IMAP user zzz@milter.aegee.org with password zzz. For this user the server returns with 20% probability the answers of LIST/LSUB/RLIST/RLSUB with 120s delay. The 120s emulate transient network errors, which I have with my internet provider (and for infrastructure reasons I have no real choice for another internet provider. This is much like using Internet on Australian islands). This user has subscriptions in the personal, shared and other users namespace, so Evolution/EDS issue three LSUB to get the mailboxes. I start and stop Evolution several times. Sometimes it does not show immediately after start the list of cached folders with corresponding cached messages, so I cannot use Evolution. (unless I first start it in offline mode).
As a matter of fact, for whatever reason a mail server can be from time to time utterly slow. It does work, but everything is very, very slow. This impacts the Evolution users, as they have cached all data from the server, but until the server reconfirms the list of mailboxes, the users cannot use Evolution. Transient network problems also prevent the users from using Evolution.
- When Evolution is started in online mode, show the cached list of folders as this is done in offline mode, until the complete list of fresh folders (for the personal, other and shared namespaces) is completely fetched from the server.