Thunderbird - Corrupt Attachments

Best Effort Support Only

This document contains instructions on using a non-Microsoft email client, such as Apple Mail or Thunderbird. Microsoft does not recommend these clients for use with Office 365, and there are often significant limitations in client functionality as a result.

Because of this, the DoIT Help Desk is only able to offer best effort support for these clients, and certain issues may require the use of a Microsoft client in order to be resolved. For more information on Office 365 client support, please see: Office 365 - Which clients/protocols will be supported?.

This document explains a work around for downloading attachments in Thunderbird.

This problem generally occurs when trying to download large attachments in Thunderbird. By default, Thunderbird downloads attachments in chunks and sometimes it doesn't download all of the chunks. This document explains how to force it to download attachments in one large chunk.

  1. Open Thunderbird and go to Tools > Options.


  2. Go to the Advanced tab > General > Config Editor....


  3. Type in mail.imap.fetch_by_chunks in the Filter field. Right click on the item that comes up and click on Toggle.


  4. Type in mail.server.default.fetch_by_chunks in the Filter field. Right click on the item that comes up and click on Toggle.


  5. If the above doesnt work, follow the same procedure but toggle mail.imap.mime_parts_on_demand to false and mail.server.default.parts_on_demand to false

Keywords:thunderbird thunder bird mozilla attachment attachments cant cannot can't download save unable corrupt corrupted downloaded   Doc ID:12472
Owner:Help Desk KB Team .Group:DoIT Help Desk
Created:2009-10-20 19:00 CDTUpdated:2020-08-13 18:22 CDT
Sites:DoIT Help Desk
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