I’ve received lots of e-mails from customers who want to run SpamSieve on an iPhone. The problems caused by a deluge of spam are only increased when using a mobile device with a small screen and slow Internet connection, and iPhone’s mail program has no built-in spam filter. E-mail is one of iPhone’s best features, and yet it can be almost useless if you have to manually remove the spams from your inbox.

I am certainly interested in developing a version of SpamSieve for the iPhone. However, at present, Apple is not allowing third-party software on the iPhone. If and when this changes, there’s also no telling whether it will be possible to integrate a spam filter into the built-in mail program the way SpamSieve integrates with Mail on a Mac. Although the iPhone’s operating system has the same core as Mac OS X, it may be that the built-in applications run in a protected environment, that it’s impractical to add commands to them (there being no menus or keyboard shortcuts), or that add-on applications are restricted in what they can do.

The good news is that you can use a Mac running SpamSieve to filter your iPhone mail today. Make sure that both the iPhone and your Mac’s mail program are setup to connect to your mail server using IMAP rather than POP. If you leave your Mac running, checking for new mail every few minutes, SpamSieve will move the spam messages out of the IMAP inbox, so that they don’t show up on your iPhone. The iPhone won’t even waste time downloading them only to find that they’re spam.

You can set your Mac’s mail program to move the spam messages to a local mailbox, in which case they’ll only be available on your Mac, or to a Spam mailbox on the server, in which case they’ll be visible on the iPhone when you look in that mailbox. All SpamSieve training must still happen on the Mac. Therefore, if SpamSieve makes a mistake and a spam message gets into your inbox, you should not delete it on the iPhone. Instead, wait until you get back to your Mac, then select the message and train it as spam.

Update (2008-08-05): The SpamSieve manual now contains some instructions for setting up Mail to filter your iPhone mail.