We are using com.atlassian.jira.service.services.imap.ImapService to create issues/comments from emails.
We are always using Outlook 2010 and each of our users has an image in the signature which includes the company logo.
When our end users send us a issue via email this image is always uploaded into JIRA as attachment.
My request for a new feature would be to filter images based upon naming,size,type (or any other pattern you can find) out of the emails. Otherwise each new comment/issue will have plenty of signature images attached.