Attachment filename truncated - Thunderbird

From MozillaZine Knowledge Base

Thunderbird may truncate the attachment's filename when displaying it. You can prevent this by adding the following to the 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.

.attachmentBox {
width: auto !important;
max-width: none !important;
min-width: 15em !important;


  • For Thunderbird 8.0 and later, change ".attachmentBox" to "attachmentitem" [1]. You may also need to apply the code to keep the attachment pane expanded to avoid that the item width is reset to the default.
  • Expect further changes with Thunderbird 10.0, which introduces variable grid width depending on the largest attachment name.

Composition window

The same problem may occur when writing a message, the attachment pane in the composition window has a fixed size and shows the attachments in a list. While the attachment pane can be extended by moving the splitter between addressing and attachment areas to the left, the default on opening the attachment pane is a constant. That default size can be increased by the following userChrome.css code [2]:

#attachmentBucket {
  width: 20em !important;

Use any other size specification instead of the 20em proposed here as desired, or auto to adjust the attachment-pane size to fit the largest attachment name [3].

Related bugs

  • Bug 654222 – Attachment list should resize to fit long names
  • Bug 630759 – Improve attachment list XBL bindings
  • Bug 697870 – Establish a maximum width for overly long file names in the attachment pane

External link

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