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Many of us have collected email messages over many years. The size of our Mozilla message folders easily grows to the point where it may be slowing down program performance and making retrieval and viewing of messages terribly unwieldy.

One school of thought is that, with today's huge hard drives and fast computers, you could safely and easily leave all those old messages in your active Mozilla profile. For the sake of organization, you'd certainly want to create some folder structure to keep the older messages out of the way of current work. You might create a new folder (or folders) periodically (say quarterly), name it something like "Q1 2005", and move messages into that folder (and sub-folders) for archiving.

One the other hand, for the same reasons that it's a good idea to backup your profile regularly, it's wise to have a backup of archived mail somewhere other than your main hard drive. So let's consider how to archive old mail to some backup media and figure out how to read it later.

(Note - see also: Mail Sync)

How it works

Mozilla stores email messages in folders within the Mail/News program component. On your hard drive those folders are actually plain-text files in Windows and stored in your profile mail folder. For more info on profiles see these links:

An example of a Windows XP Mozilla profile folder location is:

C:\Documents and Settings\[Windows User Account]\Application Data\Mozilla\Profiles\[profile name]\[random string].slt\

An example of a Windows XP Mozilla profile mail folder location is:

C:\Documents and Settings\[Windows User Account]\Application Data\Mozilla\Profiles\[profile name]\[random string].slt\Mail\[mail account name]\

When you install Mozilla and create a mail account it creates a set of standard folders:

You can also create your own folders in Mozilla. For each folder in Mozilla there is a corresponding Windows file with the exact same name. Additionally, for each mail folder there is an index file of the same name with a ".msf" file extension.

For example, you would have pairs of files in your profile for each Mozilla Mail folder you create:


The actual mail messages are stored in the mail file, the one withOUT a file extension. In short, every email from your buddy Bob that you put into the BOB folder in Mozilla are stored together in one single plain-text file on your hard drive.

Important note

You should backup your entire profile on a regular basis. See: Moz Profiles

Archiving Mail Files

It's easy enough to backup those mail files to CD or other backup media. If you like, once the backup is done and verified good, you can delete the corresponding messages/folders in Mozilla.

Great. So now we've backed up and archived all the old emails from Bob. And a month from now you want to read one or more of those emails. How do we do that? Well, remember that the mail files are simple text files. You could read them by opening them in a simple text editor such as Notepad or Wordpad. The problem is that they are not sorted, you must wade through all the header info, and HTML emails are terribly difficult to read in plain-text format. Wouldn't it be ideal to read the archived mail file in Mozilla? Of course!

In order to read the messages with Mozilla Mail you need to copy them back into your active profile's Mail folder. BUT! ... If you still have a BOB Mozilla folder in your active Mozilla Mail setup, copying that archived file back will overwrite the current one with, potentially, disastrous results.

One solution is to name the archived file something unique like BOB_BACKUP or some other name that doesn't exist as a folder in Mozilla. Then, with Mozilla Mail closed, copy that file into your active profile's Mail folder. Next time you open Mozilla Mail it will create an index (.msf file) and the folder BOB_BACKUP will appear in your Mozilla mail client. And you can browse and read the messages as you normally would.

Yeah, it's a bit of a dance to do but, once you understand what's involved, it's not that difficult.

Another Possibility

After someone asked about this on a newsgroup, I thought there might be a better solution so I did a little experimenting and came up with another approach. It works quite well and has some advantages over the method of copying an archive mail file back into the active profile.

Create a new mail account in Mozilla, filling in the forms with bogus info simply in order to create the account. Click Mail & Newsgroup Account Settings, click Add Account, and create a new dummy mail account. This account isn't going to access a real mail server or account, it's just a dummy account to serve as a kind of placeholder for our archived mail that is stored outside of the active profile. When you go through the new account creation process use fake info such as:

Account Name: ARCHIVE

Email address: archive@someplace.invalid

User Name: archive

POP server: archive.someplace.invalid

Once the account is created point the Local directory for the ARCHIVE account to the drive and folder where you stored the BOB archive. (It could be a second hard drive, a CDRW, a USB drive, even a floppy.) Click Edit - Preferences - Mail & Newsgroup Account Settings. Click Server Settings under the account you want to change (ARCHIVE in my example) and then under "Local directory:" click Browse and find the desired drive/folder where you saved BOB. Restart Mozilla, select the ARCHIVE account and there's BOB!

Before you start archiving you need to understand the structure of the Mozilla mail folders and files system.

For every Mozilla Mail folder you will have a file of the same name, e.g. BOB - and an index file BOB.msf - and a Windows folder called BOB.sbd.

If you simply copy a whole email account directory structure from your profile to the CDRW you'll have no problems. Your archived mail will have the same structure on the CDRW as it did before. If you're only copying some of the mail, pay attention to all of the pertinent files, folders and sub-folders.


When accessing a mail account's folders/messages, Mozilla wants to write files into the defined local directory. I've tested this using a CDR-W disk, a USB drive, a second hard drive, even an encrypted virtual disk. All worked well. Even if the drive or disk is not present when you open Mozilla, nothing untoward happens. The ARCHIVE account is still there but simply empty. Close Mozilla, make the drive/disk available, re-open Mozilla and ARCHIVE will be populated with all the folders and emails you've stored outside of your normal profile.

The advantages of this system are:

Using CD-R and Write-once Media

Back when I originally tested this it worked. In the most recent versions of SeaMonkey it no longer does in any of my tests.

So, you can still burn archived mail to read-only media. However, in order to access the messages you'll need to copy them to a read-write media. Make sure that the copied files and folders are not marked read-only. In Windows XP this seems to be fixed but older OS versions may not turn off the r/o attribute on files/folders copied from CD.

You can use write-once/read-only media like CD-R disk to archive BUT you must include the .msf index files when you burn the CD. If .msf files are not present when you access the message folder(s), Mozilla Mail will attempt to rewrite the index (.msf) files and store them on the CD. If you're using a CD-R disk this, obviously, won't be possible. And Mozilla may hang.

Also, with read-only media you need an extra step to view the saved archive. This is because you need to initially point the ARCHIVE account's Local folders to a writeable location (like your hard drive) so you can copy emails from your normal email account into the folders in the ARCHIVE account. That will write them into the mail files in the ARCHIVE account's writeable location. THEN you can burn them to CD-R, DVD-R, etc. However! When you want to view them from the CD-ROM disc you'll need to change the Local folders pointer for the ARCHIVE account to point to the CD-ROM. Alternatively, you could leave the ARCHIVE account's Local folders location set to the hard drive location you originally set up and copy the archived files back there from the DVD.

There are probably other ways of tackling this that I haven't thought of. If you have any comments, questions, suggestions, etc., please let me know.

This page last changed: Sunday, October 25, 2015 - 01:42 PM USA Eastern Time

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