I've been using
MailBag Assistant by Fookes Software for years. Probably the most versatile email archiver I've seen. Here's a list of features from the web site:
* Easy to use thanks to helpful wizards.
* Handles the most popular message files.
* No need to import e-mails to use them in Mailbag Assistant.
* Handles native message files even if you no longer have the original e-mail program on your computer.
* Enables you to easily share your correspondence with other Mailbag Assistant users.
* Favorites menu to quickly reopen frequently used e-mail folders.
* Message text is colored based on quote level.
* Match tool selects all messages matching your criteria.
* Filter tool shows only messages matching your criteria.
* Search tools support Boolean operators, approximate matches, and Soundex matches.
* Groups messages together meaningfully.
* Sorts grid data when column header is clicked.
* Saves e-mails into compressed message archives.
* Stores and extracts e-mail attachments and HTML messages.
* Exports e-mails as plain text, EML files, Web pages, and other formats based on customizable templates.
* Extracts information like e-mail addresses and traffic statistics.
* Provides built-in scripting language to automate tasks.
* Integrated editor for scripts and templates, with syntax highlighting.
I will say that it is fast and offers searching in just about any way you could want. You can tell it to find messages that match a certain set of parameters, extract all email addresses from those messages and then view them, print the list, store it in a file. It carries the attachments with the messages - in the archive file. I have been archiving my email messages with it in their compressed file format and also exporting all messages to EML files and zipping them up, then writing them to CD's - and now to DVD's. (Mailbag Assistant doesn't burn anything to optical drives - I use Nero for that). I need to make sure I have all email messages saved - can't afford to have a new version of my email program lose any past files, and restoring some email message stores from a regular compressed backup doesn't always work.
This is not a free program, though. $39.95, so you really have to need it, IMO.
Fookes also sells
Aid4Mail, a utility that will take all your email from most any email client and convert it to almost any other format. When I decided to stop using Pocomail and switch back to Outlook the whole process took about 15 minutes for > 15,000 messages. No preparatory work is needed. Then I switched to Thunderbird 2 from Outlook and moved them all again. Best part is it will maintain the same folder structure for you, which was a lifesaver for me. This application has four versions: Standard, Professional, Forensic, and Enterprise. If you will be converting to or from Outlook, though, you need the Professional version. Apparently there are not many other programs - if any - that will convert to and from Outlook because the PST file structure is so different from other mail apps.
Jim