Most of the Gmail interfaces have the same troubles to add attachments. Usually, you can’t add any attachments if you use Gmail mobile app, the mobile version of Gmail, iGoogle’s Gmail gadget.
But now, it is the easiest thing, because you can attach your files or folders even if you are offline (with the exception that when you’re offline you won’t be able to include inline images). Therefore, just add the attachments and send, if you have enabled Offline Gmail, you can notice that all of your mails go through outbox, regardless if you are online or offline. It is the most necessary action, when your line suddenly gets disconnected from network.

Moreover, the Offline Gmail is till a Gmail Labs feature that requires Google Gears. If you use Google Chrome, Gears is already installed. At the same time, you can read recent conversation, compose messages and view your contacts even if you don’t have internet connection.

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