Microsoft Outlook email encryption simplified


Many Exchange Server administrators balk at implementing Microsoft Outlook email encryption, because it has to be supported by both the sending and receiving email clients.

In other words, if I encrypt

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an email and send it to you, you can generally only decrypt the email by using the same software I have. If that software is proprietary or difficult to work with, the headache of encrypting email can outweigh its benefits.

A number of common free/open-source packages lessen the burden of email encryption -- but again, users have to go through the trouble of integrating them with their email packages to use them.

A creative workaround for this problem is an email encryption program for Microsoft Outlook 2003 called MessageLock. MessageLock works by compiling an email and its attachments into a standard .ZIP file that is secured with AES 256-bit encryption.

Since the vast majority of .ZIP utilities can decipher AES-encrypted .ZIP files (including WinZip, PKZip, TugZip and WinRAR), recipients probably already have the software they need to unpack and read the MessageLock-encrypted email messages.

MessageLock integrates into Microsoft Outlook and lets you access its functions through a button bar. Attachments can be separately encrypted as well.

The product can be installed on up to three computers at a time and works with any variety of email account (Exchange Server mailbox, POP3, etc.). It automatically decrypts any inbound messages encrypted with MessageLock, and can use AES-256, AES-128, Zip 2.0 or ML-256 encryption.

Users can also configure exceptions -- for instance, not to encrypt certain types of files or to only encrypt messages to specified contacts. If a recipient is also using MessageLock, the process is even more seamless. But anyone with a .ZIP utility should be able to make use of MessageLock-encoded messages.

A free and fully functional 30-day trial version is available from the manufacturer. Purchase price is $39.99. The only caveat is that the passwords used to open email need to be negotiated separately with the target users, of course.

About the author: Serdar Yegulalp is editor of the Windows Power Users Newsletter.


WinZip offers a package called WinZip Companion that does the same thing, but I believe it is more reasonably priced for what you get.
—James S.


Thanks for bringing WinZip Companion to my attention; it looks really interesting. I'll look into it for a possible future tip.
—Serdar Yegulalp, tip author


Could you please explain why this workaround is effective if any user able to open a zip file can open the encrypted file?
—Abel B.


They can open the zip file, yes, but they will not be able to open it unencrypted without the proper password. I mentioned in the article that the password for opening any given message needs to be negotiated between sender and recipient beforehand.

Obviously this isn't a complete solution for encrypted email, but it's one way to handle the problem.
—Serdar Yegulalp, tip author


I saw the thread about WinZip Companion. I just wanted to point out that MessageLock has a lot more features and flexibility than WinZip Companion.

Encryptomatic has posted a comparison at its site: "How does MessageLock compare with WinZip Companion?"
—Cory A.

Do you have comments on this tip? Let us know.

Related information from SearchExchange.com:

  • Learning Center: The Microsoft Outlook Toolbox
  • Expert Advice: Time lag opening and sending encrypted email
  • Expert Advice: Best encryption method for an Outlook .PST file
  • Reference Center: Exchange Server message encryption resources
  • Reference Center: Outlook and Exchange Server administration tools

    Please let others know how useful this tip was via the rating scale below. Do you have a useful Exchange Server or Microsoft Outlook tip, timesaver or workaround to share? Submit it to SearchExchange.com. If we publish it, we'll send you a nifty thank-you gift.

    This was first published in August 2006

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