Forwarded messages not readable

This article applies to both Thunderbird and SeaMonkey / Mozilla Suite.

Symptoms

By default, Thunderbird and SeaMonkey forward the message as an ".eml" attachment, where the name is derived from the subject line (see bugs 220646 and 380354 for a discussion on this). It doesn't copy the message into the new message, and the forwarded message cannot be edited.

Problems

• Certain e-mail clients, e.g., webmail interfaces as well as command-line clients like PINE and Mutt tend to have problems with displaying such ".eml" attachments.
• Many internet service providers block attachments with specific suffixes that are known to potentially contain viruses. This frequently includes ".eml" attachments. Thus, these attachments may be removed or the complete e-mail discarded.

Solutions

• If you do not see messages that you received as ".eml" attachment, make sure to have View → Display Attachments Inline checked.
• Send your e-mails inline rather than as an attachment: In Thunderbird, click on Tools → Options. Select the Composition category and the General tab. Select "Inline" from the drop-down box next to Forward Messages. In SeaMonkey, this setting can be found in the Edit → Preferences → Mail & Newsgroups → Composition tab.
• If the e-mail is still not readable, use plain text and disable HTML.

Workarounds

• If you have to forward a message as attachment, compose a message as usual and then drag-and-drop the message to be forwarded from the thread pane into the attachment box. This will give it a fixed file name of "Attached Message" without ".eml" suffix, which should pass ISP filtering.

Related bugs

• Bug 220646 – Forward as attachment: Attachment name is subject, without ".eml" extension
• Bug 269826 – Problems related to message/rfc822 attachment (forwarded mail) in a mail and ".eml" file
• Bug 312025 – Filter action Forward Message to sends the mail as attachment regardless of option
• Bug 380354 – TB2 adds ".eml" extension to attached messages, causes virus scanner to complain; TB1.5 was OK

External links

• The ForwardAs extension adds a submenu to the Forward button that lets you choose between forwarding inline or as an attachment.
• The NotTo extension adds a NotTo Forward command to the Forward button that prevents the message being sent to the original sender.