The hint that Phil gives is correct, but after the message were downloaded, one must first disconnect the mailbox before one can switch it to offline mode by clicking the "Offline mode" button.

The "problem" is when an account has several mailboxes. One must disconnect them one after each other and then switch them to offline mode. And vice versa when re-connecting. This is time consuming. So...

1. Is there a way to switch all mailboxes from an account to connected/offline simultaneously ?

2. Is there a way to make that clicking the "Offline mode" button disconnect automatically a mailbox and switch it to "offline" without having to first disconnect manually ?

No problem if this does require some programming.

I'm using version 4.52 because it's more lightweight than upper versions and I think it's web renderer is independant from MSIE.

I'm having a great problem with Pegasus Mail 4.41 that prevents from reading my IMAP mails offline. While all my IMAP messages are cached and no special performance setting is enabled, Pegasus Mail just doesn't list my IMAP folders (INBOX, Junk, etc) in the offline mode, which prevents from reading cached messages as all messages are in IMAP folders.

When I'm online, all works well and Pegasus Mail can show the folders:

But when I'm offline and I click the "offline" button in the IMAP profiles list, these folders don't appear and there's only the name of the IMAP box:

Double-clicking the name of the box will just change the mailbox icon but nothing else will change.
IMAP folders do appear only if I:
1. Connect to the IMAP mailbox - so you have to be online!
2. Close the mailbox.
3. Turn off the Internet connection so that Pegasus mail can't access the IMAP server.
4. *not closing Pegasus mail!*
5. Click the "offline" button in the IMAP account list. Then folders appear, which probably means that Pegasus Mail doesn't remember the IMAP folder's names when it is closed.

The problem is that I found *no way* to actually read my cached messages offline. There's no problem with cache files, Pegasus Mail tells that index files are OK and I read .pmc files: they indeed contain all my cached messages.

Does anyone know a trick to read those cached messages?

I suppose that you've already read that in the help file :

English version:

In offline mode, the IMAP profile is read-only - you cannot delete, change or add messages or folders in the profile while offline.

To use an IMAP profile offline, you must already have connected to it online at least once. Certain options on the "Performance" page of the IMAP definition editor, most notably the Fast Listing and Subscribed folders options, will prevent you from using a profile in offline mode if they are set. Actually using the profile offline is simplicity itself - simply click the Use offline button in the profile list window instead of the Connect button.

Hint: if you want to make sure that all the messages in a folder are available for use in offline mode, right-click the folder in the list of folders and select the Cache all messages option from the right-click menu.

Version française (vu qu'il semble que tu utilises PM en français) :

En mode hors ligne le profil IMAP est en lecture seule, vous ne pouvez pas effacer, modifier ou ajouter des messages dans le profil tant que vous êtes hors ligne. 

Pour pouvoir utiliser un profil IMAP hors ligne vous devez vous y être connecté en ligne au moins une fois. Certaines options de la page "Performance" de la définition du profil IMAP, notamment Listage rapide et Dossiers sélectionnés, vous empêcheront d’utiliser un profil en mode hors ligne si elles sont activées. L’utilisation d’un profil hors ligne est simple, il suffit de cliquer sur le bouton Hors ligne dans la fenêtre de profil au lieu du bouton Connecter.

Truc : Si vous voulez être sûr que tous les messages d’un dossier seront disponibles en mode hors ligne il suffit de faire un clic droit sur le dossier et de choisir l’option Cacher tous les messages.