From MozillaZine Knowledge Base

Thunderbird 2.0 to 7.0

Thunderbird 2.0 displays large icons for the attachments (this default was reverted to small icons with 3.0). You can slightly reduce the size by setting mailnews.attachments.display.largeView to false using the Config editor.

Thunderbird 8.0 and later

The old boolean preference has been replaced by an integer preference mailnews.attachments.display.view to accommodate more modes. There doesn't appear to be any migration code initializing it to reflect your previous choice, thus defaulting to "small" again after upgrading from a previous versions. The values of that preference are:

• 0 — small icons left to the attachment name, size to the right of the name
• 1 — large icons left to the attachment name, size underneath the name
• 2 — large icons on top of the attachment name with size underneath

Remove icons completely

If you don't need the icons you can add the following to the optional userChrome.css file in the chrome subdirectory in in your profile folder. The file does not exist by default, so you may need to create it before you can start adding your preferences.

/* Remove icons in Message pane Attachment view box */
.descriptioncell-icon {
display: none !important;
}

/* Display attachment filenames full length */
.attachmentBox {
-moz-appearance: none !important;
width: auto !important;
}

Note: This code may no longer work with Thunderbird 8.0 due to changes in the underlying attachmentlist binding.

Related bugs

• Bug 511592 – Attachment area is very big (change in default, effective TB 3.0)
• Bug 630759 – Improve attachment list XBL bindings (effective TB 8.0)

See also

• Attachment pane height - Thunderbird