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MozBackup fail – file size limit cripples large messagebase backups


I hate to do this to a cool Open Source product like MozBackup, but it really let me down the other day when I needed to transfer my email message base across from one machine to another. The backup file was fine, but contained only a small part of my data. Apparently the program can only cope with messagebases up to 4 GB in size. My messagebase is around 12 GB, hence the problem with only getting a portion of my messages in the archive file.

In the end I had to ditch MozB and go for the very excellent Static Thunderbird Backup which coped effortlessly with the 12 GB and moved everything over beautifully. Sorry Moz guys, but you really need to sort out that file size limit and fast. In this case $24.95 commercial beat out free OSS big time.


  • May I ask why you didn’t just copy your Thunderbird email folder? A simple batch file can also back it up, or the fantasic free Karen’s Replicator for regular and quick email backups – I actually keep my TB email folder on a separate hard drive from my C Drive so a quick coy and paste to a USB stick can easily be done.

  • Hey dude.
    You should look into IMAP, but that of course is only my humble opinion.

  • I just discovered that MozBackup wasn't backing up the entire tree. I've lost 6 months of email. I really liked the tool, but it has let me down… badly.

    When it tells me the backup is complete I would expect it to be correct. If a backup is going to exceed an arbitrary limit then have the software TELL YOU it couldn't back everything up.

    Thanks for the link to Static. Just used it and impressed. Backed everything up, uploaded FTP copy and wrote to CD too. Best part is… ALL my data is there!

  • I could not agree more. How can Thunderbird / MozBackup let its users run into such a trap? Why not inform about the 4GB limit on the download page right next to the download button? Why not tell the user that a limit is exceeded? I just lost about 5 GB of e-mail data. What a miserable service. How disappointing!

  • Hi, It uses zip compression which has the limit. They need to change to rar or some tar/gzip for compression instead. :)

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