IS-FOX Encrypt - The Easy Way to Encrypt E-Mails in Microsoft Outlook

With IS-FOX Encrypt, your employees can send e-mails securely – without certificates or the exchanging of keys. The symmetrical end-to-end solution is above all user-friendly. After all, your employees will only encrypt e-mails if it happens on the push of a button, otherwise confidential information and files will continue to be sent unencrypted, an incalculable risk for your company. This is why IS-FOX Encrypt is:



The attachments or entire e-mail are encrypted securely. The password is automatically sent as a text message via a second communication channel.

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Encrypted ZIP files can be opened on virtually all terminals. IS-FOX Encrypt also offers users an intelligent Password Management tool.



IS-FOX Encrypt is very cost-effective for commercial users and offers attractive volume discounts. Private users can use IS-FOX Encrypt free of charge.

What You Need to Know about IS-FOX Encrypt

Why should you encrypt your e-mails?

An e-mail is like a postcard: it can be read in plain language by lots of people en route from A to B, for example the administrator and e-mail provider, and people linking into the line of transmission between sender and recipient. This is why you should protect and encrypt confidential that could cause considerable damage if disclosed to third parties.

Why should you use IS-FOX-Encrypt?

Why should you use IS-FOX Encrypt?

Encrypting e-mails with IS-FOX Encrypt is user-friendly and avoids obstructing everyday work life. The encryption technology from IS-FOX Encrypt works without PGP or S/MIME, as the setting up and use of very secure, asymmetrical solutions for e-mail encryption are unfortunately too complex for most users. Asymmetrical encryption generally fails if:

  • the e-mail recipient does not support asymmetrical encryption
  • another form of e-mail encryption is used (e.g. PGP vs. S/MIME)
  • the key isn’t found
  • the certificate is invalid

If both the sender and recipient are using IS-FOX Encrypt, the e-mail is completely and permanently encrypted on the push of a button and then simply browsed und archived. The e-mails and attachments encrypted in a highly compatible ZIP format can be opened on almost any terminal.

If you are already using S/MIME then we have the perfect addition for you: IS-FOX E-Mail Classification activates S/MIME encryption from your chosen confidentiality level. If the recipient’s key cannot be traced, IS-FOX E-Mail Classification immediately offers ZIP encryption from IS-FOX Encrypt as a replacement.


  • Symmetrical end-to-end encryption using a password.
  • Supported operating systems: Windows Vista, 7, 8 and 10 (32 or 64-bit).
  • Supported versions of Microsoft Outlook: 2010, 2013 or 2016.
  • IS-FOX Encrypt can be operated via terminal servers.
  • The entire e-mail or alternatively only the attachments are encrypted in a ZIP file.
  • Choose from the highly compatible ZIP 2.0 or the particularly secure Advanced Encryption Standard (AES 256).
  • Automatic, encrypted transmission of the password to the SMS provider where it is fed in as a Premium SMS with delivery guarantee.
  • Encrypted storage of the passwords used in the Password Manager tool with access control managed via user levels in Windows.
  • Rollout of the Microsoft Outlook plug-ins via software distribution or Microsoft Group Policies.
  • Simple upgrade to IS-FOX Classification.

Price list for commercial use:

Purchase price, incl. one-year update guarantee

Price list

All prices net plus statutory VAT.

You can calculate the overall cost of your licence needs with our IS-FOX Encrypt licence-calculator.

You also receive SMS contingents for the optional sending of passwords from 10 ct/SMS in the IS-FOX Encrypt-Portal.


How to obtain your commercial version of IS-FOX Encrypt:

  •     Download the demo version and test IS-FOX Encrypt for 30 days free of charge.
  •     If you’re satisfied, you can purchase licences in the IS-FOX Encrypt Portal.
  •     Convert the demo version into a full version with your licence key.
  1. Download the demo version of IS-FOX Encrypt.
  2. “Purchase” a private licence for EUR 0 in the IS-FOX Encrypt-Portal.
  3. Convert the demo version into a full version with your private licence key.
  • IS-FOX Encrypt stores all of your passwords encrypted in the integrated Password Manager tool and displays them on request.
  • A standard password is stored for each recipient. IS-FOX Encrypt then suggests this standard password automatically the next time an e-mail is sent to the same recipient.
  • If the e-mail is being sent to several recipients, the sender can create a group password and use it every time e-mails are sent to this group.
  • The sender can always display the password for every encrypted e-mail sent.
  • The user clicks on “Send encrypted”.
  • The entire e-mail or just the attachments are then automatically encrypted in a ZIP file.
  • AES-256 can be selected for particularly secure encryption.
  • A password generator automatically creates a password (that the user can of course change) the first time an e-mail is sent.
  • At the same time, the recipient’s mobile phone number is retrieved from the Outlook address book.
  • The password is automatically sent (on request) to the recipient as a text message.
  • The password used is stored encrypted in the IS-FOX Encrypt Password Manager and re-used when a new e-mail is sent to the same recipient.

If both the sender and recipient are using IS-FOX Encrypt, the e-mail is completely and permanently encrypted on the push of a button.

Test IS-FOX Encrypt free of charge? Download


The IS-FOX Encrypt Partner Programme

Help your clients to protect sensitive corporate data by offering them a simple e-mail encryption tool in Outlook. Join our IS-FOX Encrypt Partner Programme. As a partner, only minimal effort is required to operate and manage IS-FOX Encrypt. The benefits of an IS-FOX Encrypt partnership:

  • No initial investment, as an IS-FOX Encrypt partnership is free of charge.
  • Free use of IS-FOX Encrypt partner licences.
  • Marketing and operational documents.
  • Convenient client management in the IS-FOX Encrypt Partner Portal.
  • Second-level support directly from the manufacturer.

Acquire additional licences? Book SMS contingents?

You can manage your IS-FOX Encrypt accounts conveniently yourself in the IS-FOX Encrypt Portal

IS-FOX Encrypt-Portal

E-mail encryption with IS-FOX Encrypt – Technical Questions

What types of encryption are there?
IS-FOX Encrypt always encrypts as a ZIP package. You have two options regarding encryption strength:

  • “High compatibility”: IS-FOX Encrypt uses the weaker ZIP 2.0 algorithm to encrypt. The advantage is that almost all recipients can open the file without needing any additional software. However, a file encrypted using ZIP 2.0 can be cracked with hacking tools in the space of a few hours, so you should avoid using this option for highly sensitive information.
  • “High security”: IS-FOX Encrypt uses the strong AES-256 algorithm to encrypt. The advantage is that the encrypted file can only be cracked with a lot of time and immense effort, depending on the password length. However, the recipient also needs IS-FOX Encrypt or another software program that can decrypt AES-256 (e.g. package programs such as Winzip, 7-zip or WinRar) in order to open the file.

Does the recipient also need IS-FOX Encrypt?
No. Encrypting e-mails with IS-FOX Encrypt makes the recipient’s everyday work life simpler, for example because the password is pre-set and e-mails can be encrypted permanently. In order to open an e-mail encrypted with IS-FOX Encrypt, a recipient needs:

  • For “high compatibility”: only an operating system that can open ZIP files. Every Microsoft Windows operating system from the XP version upwards can do this, for example.
  • For “high security”: a package program (e.g. Winzip, 7-zip, WinRar or similar) that can open files encrypted using the strong AES-256 algorithm. 7-zip, for example, is a suitable package program that is free of charge. If you encrypt on a “high security” basis, the e-mail recipient will be informed that this type of program is needed to open it.

Is it always necessary to send a text message?

No. The sending of text messages is optional and needs to be activated separately when sending the e-mail. Most encrypted e-mails are sent without an additional text message, as the recipient has received the password via another communication channel (e.g. by telephone) or already knows it.

How are text messages sent?

IS-FOX Encrypt sends the text-message data encrypted to the IS-FOX Web Service, which then decrypts the data and transmits it (again via an encrypted channel) to one of several SMS providers. The text message is then fed into the GSM network and sent to the recipient.

If your Internet connection is down when you send the text message, an e-mail with the encrypted message will be generated and stored in the Outlook outbox folder. It will be sent to the IS-FOX server when the Internet connection returns and processed as outlined above.

How is the sending of text messages billed?

You buy an SMS packet online in the IS-FOX Encrypt Portal (e.g. 100 text message for EUR 10 plus VAT) and can then use this SMS contingent.

How is IS-FOX Encrypt installed?

  • Single-user version: you install IS-FOX Encrypt via the set-up program. IS-FOX Encrypt checks if all the necessary components are available. Any missing components in the operation system (e.g. Microsoft .Net, PIA or Visual Studio Tools for Office) are automatically installed with IS-FOX Encrypt.
  •  Company-wide rollout: you can roll out IS-FOX Encrypt via your usual software distributor or Microsoft Group Policies. You also have the option of managing your IS-FOX Encrypt settings centrally via the IS-FOX Encrypt Portal.

Are administration rights needed for IS-FOX Encrypt?

Administration rights are needed for the installation of IS-FOX Encrypt. It can then be implemented using normal user rights.

What do I need to take into account when installing IS-FOX Encrypt into Office 2013/2016?

There are no independent Primary Interop Assemblies (PIA) for Office 2013/2016 that can be installed with IS-FOX Encrypt. The PIA 2013/2016 is automatically installed with Office 2013/2016 unless the component has been deliberately excluded at the installation stage. If the PIA 2013/2016 has not been installed with your Office 2013/2016 system, you can add the component manually: go to the Windows Control Panel then in Programs and Functions select Office 2013/2016 and “Change”. The “.NET Programmability Support” component must be installed underneath Outlook.

What happens if a user gets a new computer?

  • For single-use computers without a Windows domain (private individuals or small enterprises): you can install IS-FOX Encrypt on the new computer and enter your licence key. Activation then takes place automatically via the e-mail address. The password database is linked to the Windows user so it can’t just be transferred to the new computer. Export your password database from the old system and import it into the new one.
  • For company computers in a Windows domain: all the important IS-FOX Encrypt files and settings are stored in the user profile. If this profile moves to a new computer then all passwords and settings are kept. If the user is deleted in the Active Directory, the database can no longer be decrypted.

What types of licences are there?

  • Private licence: a free licence for private use for one e-mail address.
  • Commercial licence: a paid-for licence for companies; prices are staggered depending on licence scope. The commercial licence facilitates central management and rollout.

Is the licensing for IS-FOX Encrypt user or terminal-based?

Licensing is based on e-mail addresses. The user Sam Sample, for example, can license IS-FOX Encrypt on his e-mail address He can install IS-FOX Encrypt on as many terminals as necessary but only use it with this e-mail address.

How is the e-mail address checked?

  • Private licence: IS-FOX Encrypt uses the e-mail address you used to register in the IS-FOX Encrypt Portal, so if you registered in the IS-FOX Encrypt Portal with, you can only link your IS-FOX Encrypt licence to this e-mail. You can change the e-mail address in the portal at any time if you want to link your licence to another e-mail address.
  • Commercial licence: IS-FOX Encrypt uses the domain of the e-mail address you used to register in the IS-FOX Encrypt Portal, so if you registered with, you can link your IS-FOX Encrypt licence to all e-mail addresses in the “” domain. You can add as many domains as necessary (, or under “Settings” in the IS-FOX Encrypt Portal.

What does “activation” mean?

After the licence key has been entered, IS-FOX Encrypt links itself to the licence server and assigns the e-mail address to the licence. The software is then officially released for use. IS-FOX Encrypt checks the validity of the licence at regular intervals.

Is activation absolutely necessary?

No activation is needed during the 30-day period of the demo version but it is necessary for continued use once the demo period is over.

What system requirements does IS-FOX Encrypt need?

  • Operating system: Microsoft Windows Vista, 7, 8 or 10 (in a 32 or 64-bit version). Any additional components that are needed (Microsoft .NET 4.5, VSTO, PIA) will be installed with IS-FOX Encrypt as required.
  • E-mail client: Microsoft Outlook 2007, 2010, 2013 or 2016.

What are .NET, VSTO und PIA and why are they needed?

  • .NET is the Microsoft platform for developing and operating application programs. From Windows 8 upwards,.NET 4.5 is already included in the Windows operating system.
  • The Visual Studio Tools for Office (VSTO) serve as a runtime environment for .NET applications in Microsoft Office. They have been part of the Microsoft Office package since Office 2013.
  • The Microsoft Primary Interop Assembly (PIA) is the data-exchange interface between .NET and Microsoft Office. It has been part of the Microsoft Office package since Office 2013.

Is IS-FOX Encrypt also available for Mac OS?

No, IS-FOX Encrypt requires Windows and .NET as key components.

Does IS-FOX Encrypt need a Microsoft Exchange server?

No. IS-FOX Encrypt is purely a user-based software program for Microsoft Outlook without any components on the mail server.

Does IS-FOX Encrypt also work with Office 365?

Yes and no. IS-FOX Encrypt works on the client components of Office 365, i.e. if Microsoft Outlook is installed on the terminal. The web app from Outlook is currently not supported.

In which languages is IS-FOX Encrypt available?

IS-FOX Encrypt is currently available in German and English. The choice of language takes place automatically. A German Office system shows IS-FOX Encrypt in German while all other language versions of Office show IS-FOX Encrypt in English.

IS-FOX Encrypt is not showing or loading in Outlook.

You’ve installed IS-FOX Encrypt and are starting up Outlook but IS-FOX Encrypt is not displayed. In this case, please open the Outlook Add-in dialogue:

  •     Outlook 2007: Extras menu – Trust Center - Add-Ins
  •     Outlook 2010 and 2013 file - Options - Add-ins

Outlook Add-in dialogue

  • IS-FOX Encrypt is listed under inactive add-ins:
  • Select “Go to - COM Add-in" in the add-in dialogue and activate the tick in front of IS-FOX Encrypt. The “Load behaviour” should be “Load at startup”. Confirm with OK. IS-FOX Encrypt should now be loaded. If not, open the add-in dialogue again via "Go to - COM Add-in", tick IS-FOX Encrypt and check the load behaviour message. If an error is displayed (... a runtime error occurred), this means that a necessary Microsoft component (.NET. VSTO, PIA) is faulty.
  • IS-FOX Encrypt is listed under deactivated add-ins:
  • If, for whatever reason, Outlook closes unexpectedly (e.g. it crashes), Microsoft makes the add-in that was running at the time of the crash responsible for it, regardless of whether the add-in was actually responsible or not. In this case, Microsoft deactivates the add-in. Select "Go to – Deactivated elements" in the add-in dialogue and re-activate IS-FOX Encrypt (= release it from the exclusion zone). IS-FOX Encrypt will then initially be listed under “Inactive add-ins” and must then be activated as set out above.
  • IS-FOX Encrypt isn’t listed at all:
  • An installation error has clearly occurred. Please re-install IS-FOX Encrypt.

The mobile phone number of a recipient isn’t showing, even though it’s listed in Outlook Contacts

This behaviour can occur if you use Microsoft Exchange and write to a recipient who is also listed in the Microsoft Exchange global address list (GAL). Outlook differentiates between the e-mail addresses in the Exchange GAL and the local Outlook Contacts list. This isn’t obvious when you type an e-mail address, however, so it may be that you’re writing to a “Sam Sample” and, while you’re typing, the “auto-complete” applies the address for Sam Sample in the Microsoft Exchange address list. If no phone number has been stored there, no phone number will appear, even if the same e-mail address with a phone number is stored in the local Contacts list.

Solution: Use the “To…” button to select the recipient from the local Outlook Contacts list or enter the mobile phone number once in the Exchange address list. IS-FOX Encrypt will then assign this number to the e-mail address.

We are planning a function extension for a future version of IS-FOX Encrypt so that all available address books are searched automatically.

Other questions? Interested in the Partner Programme?

Then call us on (+49 89 890 63 62-0) or send us a message.