Get more from email on the iPhone
Avoid confusion Don't give two email accounts the same name, because Mail will get confused and copy the settings from one account to the other. And you can't fix the situation by simply renaming one account; you'll need to delete one of the accounts and then re-create it.
Mark read messages as unread There doesn't appear to be any way to mark read messages as unread on the iPhone - but there is. While viewing a message, tap on Details, which reveals a Mark As Unread option; tap on it, and the next time you view your inbox, the message will display a blue dot, which indicates that the message has not been read.
Recover 'lost' emails If you try to send an email but the iPhone can't get network access, you might think your message has disappeared completely. But don't worry: a temporary Outgoing folder is created to hold the message. You can access this folder from the main screen of the sending account; the folder will disappear once network access is available and the message is sent.
Create email folders Well, actually, you can't create email folders on the iPhone. But what you can do with an IMAP email account is create folders on the IMAP server - for example, if you have a .Mac account, using the .Mac webmail interface. Those folders will then appear on the iPhone, and their contents will - eventually - be synched between the iPhone and the server.
Save email drafts If you want to save a message you're working on so you can come back to it later, tap on Cancel. Instead of deleting the message immediately, Mail pops up a dialog box with the options Save, Don't Save, or Cancel.
Tap on Save and the message will be placed in your Drafts folder. (If your account doesn't currently have a Drafts folder, Mail will create one.)
Don't be alarmed if the message doesn't appear in Drafts immediately, however; it sometimes takes several minutes for the draft message to show up.