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my msgFilterRules (?) file becomes unreadable and a new one is started (I was up to 740 filters this last time it did it). How can I prevent this?

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  • Last reply by Wayne Mery

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A few months back I started using message filters to cut down on my spam and reduce my inbox clutter. Sometimes (maybe 4 times now), when I start Thunderbird, an Alert message appears saying: "Your filters do not work because the msgFilterRules.dat file, which contains your filters, could not be read. A new msgFilterRules.dat file will be created and a backup of the old file, called rulesbackup.dat, will be created in the same directory." Is there a way to fix this backup file to get my filters back? I was up to about 740 filters and probably won't bother using message filters if I can resolve this...

Any ideas on why this is happening or how to prevent it from happening again?

Any help is most gratefully appreciated.

A few months back I started using message filters to cut down on my spam and reduce my inbox clutter. Sometimes (maybe 4 times now), when I start Thunderbird, an Alert message appears saying: "Your filters do not work because the msgFilterRules.dat file, which contains your filters, could not be read. A new msgFilterRules.dat file will be created and a backup of the old file, called rulesbackup.dat, will be created in the same directory." Is there a way to fix this backup file to get my filters back? I was up to about 740 filters and probably won't bother using message filters if I can resolve this... Any ideas on why this is happening or how to prevent it from happening again? Any help is most gratefully appreciated.

All Replies (3)

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Message filters are really best at filtering eg: good emails into various folders for organising purposes.

You should consider using Thunderbirds Junk Mail controls to deal with Junk.

Writing numerous Filters (and 700 + is a lot) to deal with the ever increasing variations is not the best method when there is already a tool designed to do that. I would suggest that you read info on setting up and training the Junk Control Filter.


Info on Message Filters:

To access Profile folders and locate the message Filter files: Make hidden Folders visible

In thunderbird Help > troubleshooting Information click on 'Show Folder' button a new window opens showing your Profile folder.

Close Thunderbird now. click on Mail folder click on mail account folder this is where the 'msgFilterRules.dat' file is located. the backup of the old 'msgFilterRules.dat' file, called 'rulesbackup.dat', will be located in the same directory.

You could open the 'rulesbackup.dat' file using a text editor eg: Notepad. Copy/paste all into the new 'msgFilterrules.dat' file. (open in Notepad) Save the file. close opened dat files.

Is there is a 'tmprules.dat' file - if yes, delete this file.

Open Thunderbird.

Modified by Toad-Hall

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Thank you for the reply Toad-Hall, it has a lot of useful information. I do use the message filters to automatically send e-mails to numerous different folders, as well as dealing with Junk (I found it does cut my spam considerably, although I do still get some). In any case, it be nice to know why this is happening, so I can prevent it. Having said that, I will try to find the backup msgFilter file and see if it can be fixed and restored, which would be really nice... I will also check the Junk-management information, although it was the way I was handling spam all along, maybe there's something new I'm not aware of that would be useful.

Much thanks for your help and let me know if you have any ideas on how to prevent this from happening in the future

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btw, you would be better protected if you back up your Thunderbird profile on a regular basis.