MySQL "Group By" and "Order By"

I want to be able to select a bunch of rows from a table of e-mails and group them by the from sender. My query looks like this:

SELECT 
    `timestamp`, `fromEmail`, `subject`
FROM `incomingEmails` 
GROUP BY LOWER(`fromEmail`) 
ORDER BY `timestamp` DESC

The query almost works as I want it — it selects records grouped by e-mail. The problem is that the subject and timestamp don't correspond to the most recent record for a particular e-mail address.

For example, it might return:

fromEmail: john@example.com, subject: hello
fromEmail: mark@example.com, subject: welcome

When the records in the database are:

fromEmail: john@example.com, subject: hello
fromEmail: john@example.com, subject: programming question
fromEmail: mark@example.com, subject: welcome

If the "programming question" subject is the most recent, how can I get MySQL to select that record when grouping the e-mails?