How to I garble (make unreadable) text in a photo?

I need to post a picture of my e-mail inbox to support group, but I don't want the e-mail addresses and Subject lines to be readable. I'm pretty sure that I can select the text area and apply a filter to that area, but what filter will distort the text enough to make it unreadable, while still showing that there is text there? (Like what they do to photos to make people unidentifiable.)