Pre-Migration Preparation - How-Tos

How to Find Mail Account and Message Sizes

Check Message Size

Individual messages larger than 25 MB, including attachments, will not migrate. Here's how to check the sizes of your messages in Thunderbird:

  1. Right-click on your folder at the very top of your mailbox list and select "Search Messages."
  2. Be sure the "Search subfolders" box is checked and that "Run search on server" is not.
  3. Click the first drop-down (which currently says "Subject") and select "Size (KB)"
  4. In the second drop-down, select "is greater than"
  5. In the third field type: 20000
  6. Click the "Search" button
  7. When a list of results comes up, you can see the sizes by clicking the little drop down icon at the end of the row of list headings and selecting "Size"
  8. A column of sizes will appear. You may have to adjust the column widths to see it. Double-click on a message to open it.
  9. If you would like to create new folders for these attachments, do that before continuing.
  10. You can select more than one attachment to the same message by holding down your shift key while you select them. Right-click on the selected attachment(s) and select "Detach."
  11. After the file(s) have been copied, you will receive a warning message that they will be permanently deleted. Select "OK." It may not look like the attachments have been deleted, but after you close out your search and restart Thunderbird, they will be gone.

Check the Combined Size of Your Mail Accounts

The combined mail in your CalMail EECS and CalMail accounts must not exceed 25 GB. You can check the size of your mail in each account by going to the CalMail web interface.

Transferring Personal Contact Groups, Signatures and Filters

Personal Contact Groups

Personal Contact Groups can be exported and imported from Thunderbird to bMail.

In Thunderbird:

In bMail:


You will need to make a copy of your existing Thunderbird signature and recreate it in bMail.


You will need to print out your filters and recreate them in bMail by hand.

  1. Print out filters
    • If they are on Thunderbird take a screenshot.
    • If they are on CalMail
      • Go to the CalMail website, choose "Manage Your Account" on the left, select the account in the right-side pane.
      • Select "Filters" on the left, and print out that page.
  2. Create filters in bMail

Back to CalMail to bMail Migration main page

Jun 06, 2013 13:55

EECS Administrative Computing Group |
University of California, Berkeley