How do I make a customized ringtone for an email sender?

Actually there is a non-direct way. It involves creating a new Profile (you could name it for that contact, let’s say “Bob”). In that Profile, named “Bob”, set the ringtone for SMS, mail, phone, etc., that you want from that contact to notify you.

Next, in your normal “active” profile (i.e., the profile you use) scroll down to advanced and “Use Active Profile Except for:”.

Here you will create an exception, by clicking Menu, New Exception. Name the exception “Bob”. In the FROM field, click Menu to Add Name, where you will place that contact entry name.

Next, under “Use Profile” you will click to change that option to the profile named “Bob”. Also, again, add the custom phone tune you want “Bob” to have and make sure you have and enable that exception with the checkmark in the box.

Voila, now when your “Bob” calls, emails or sends an SMS, you will be alerted by its own customized notification.