Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

What is the maximum number of messages/folders that Thunderbird can handle?

  • 1 reply
  • 5 have this problem
  • 83 views
  • Last reply by Matt

more options

I am considering migrating from Outlook (2007) to Thunderbird (on a MsWin7-Ultimate 64-bit PC). Unfortunately I have a lot of historical Emails that I still have and periodically reference; currently these are in several PST files. From reading some of your prior support questions I found out that Thunderbird uses one monolithic mail data-base, apparently mapped into the normal file/folder structure of the Operating System (i.e., nothing that user selectable, like the PSTs offer); but that Thunderbird will suck in all of the mail from the Outlook PSTs at installation time, presuming that the are all opened at the time of Thunderbird installation (?).

QUESTION: That being the case, are there ANY LIMITS on the number of folders or messages that Thunderbird can manage?

I am considering migrating from Outlook (2007) to Thunderbird (on a MsWin7-Ultimate 64-bit PC). Unfortunately I have a lot of historical Emails that I still have and periodically reference; currently these are in several PST files. From reading some of your prior support questions I found out that Thunderbird uses one monolithic mail data-base, apparently mapped into the normal file/folder structure of the Operating System (i.e., nothing that user selectable, like the PSTs offer); but that Thunderbird will suck in all of the mail from the Outlook PSTs at installation time, presuming that the are all opened at the time of Thunderbird installation (?). QUESTION: That being the case, are there ANY LIMITS on the number of folders or messages that Thunderbird can manage?

Chosen solution

None I am truly aware of, other than available disk space on the computer.

The 4Gb (per folder) limit on local folders has been lifted, but I am not sure I trust the fix. SO think of 4Gb as a limit on folder size.

I am unaware of any practical limit to the number of accounts. I have heard of hundreds and have dozens personally.

I suppose the limit of the files system file size still applies, but as that is 16Tb in windows 7 and 256Tb in Windows 8 I don't think that is really a concern. (I have not heard of a single hard disk that size yet).

With the mailDir optional structure for storing mail in Thunderbird 38 (one mail one file), then even that limit is moot, other than for the global index and folder indexes. Note that it is an option for "New" accounts, not imported ones, and it is not the default.

Read this answer in context 👍 2

All Replies (1)

more options

Chosen Solution

None I am truly aware of, other than available disk space on the computer.

The 4Gb (per folder) limit on local folders has been lifted, but I am not sure I trust the fix. SO think of 4Gb as a limit on folder size.

I am unaware of any practical limit to the number of accounts. I have heard of hundreds and have dozens personally.

I suppose the limit of the files system file size still applies, but as that is 16Tb in windows 7 and 256Tb in Windows 8 I don't think that is really a concern. (I have not heard of a single hard disk that size yet).

With the mailDir optional structure for storing mail in Thunderbird 38 (one mail one file), then even that limit is moot, other than for the global index and folder indexes. Note that it is an option for "New" accounts, not imported ones, and it is not the default.

Modified by Matt