I need to figure out how to get a diverse sample of emails with inline images in them. Our web application has to be able to identify inline images in email and then display the email and image in a discussion format. I am looking for any suggestions on how and where to get as many unique examples of this as possible.
Host an Open Beta, soliciting such emails.
You need to clarify your question. What do you mean by diverse sample of emails. Are you talking about different encodings, emails from different providers, different fonts, etc., or are you just talking about emails with embedded images? Also, is there a size limitation on the inline images?
A simple approach may be to generate random strings of words then randomly insert images at 1 or more points within the message body. Parameterized test data generation is a very potent way to increase data coverage and increase test variability.
As for where to get the images...the Internet has an amazing amount and variety of images that are publicly available.