User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.4) Gecko/2008111922 GranParadiso/3.0.4 Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.17) Gecko/20081 109 Thunderbird/2.0.0.17 Mnenhy/0.7.5.666 When there is an e-mail attached in another e-mail, it is possible to open it, but it's not possible to view its source. This can happen when a mail server report an error back to you, or when you get a forwarded message (with the forwarded message attached, not inline). If you right-click on the attached e-mail, you can open it, there is no option to view its source. When the attached e-mail is opened, the View->Message Source (Ctrl-U) is not available. Reproducible: Always Steps to Reproduce: 1. Send yourself a message containing an attached e-mail (.eml) 2. In this message, open the attachment 3 [review]. Try to view its source, you can't Actual Results: You can't view the message source Expected Results: You should be able to view the message source Happens on Thunderbird 2 and 3