Recently, we have received an increasing number of requests that users who use Kerio Connect receive an error message in the REDDCRYPT Outlook plugin when they want to send an encrypted email.

For this reason, we installed the mail server in the test lab, searched for errors and found a faulty syntax in the Kerio Outlook Connector.

We have summarized why the error occurs and how to solve it for you in the following article.

What causes the error message “Unable to detect the sending address”?

If you send an email via the REDDCRYPT Outlook plugin, this email is digitally signed before it is sent. This is a security feature. A digital signature is used so that the central REDDCRYPT service recognizes that this email was sent by a registered REDDCRYPT user and that it is not a fake email.

In order to digitally sign the email and thus confirm the authenticity of the sender, our Outlook plugin needs to know who the sender of the email is. Our Outlook plugin asks your Outlook this “question” before the encryption process and normally receives the user’s email address in response.

The error message “Unable to detect the sending address” always occurs if the reply from your Outlook is not an email address or is not a correctly formatted email address.

Incorrect syntax in the Kerio Outlook Connector (Offline Edition)

In our test lab, we installed a test version of the Kerio Connect mail server (version 9.2.8-4367, installation file kerio-connect-appliance-9.2.8-4367-vmware-amd64) and the Kerio Outlook Connector (Offiline Edition) client in version 9.3.1-5365 (installation file kerio-connect-koff-9.3.1-5365-win64).

When we tried to send an encrypted email, we also received the error message described above.

During testing, we noticed that the sender address displayed looks “strange”.

Normally, the sender field only contains the email address and no display name. And if a display name is displayed in emails, this is usually separated from the actual email address with brackets or quotation marks. This indicates what is the email address and what is the display name. Examples of this are

• ds@firma.de
• “Dieter Datenschutz” (ds@firma.de)

Incorrect would be ds@firma.de Dieter Datenschutz or ds@firma.de – Dieter Datenschutz, as there is no (technical) separation between email address and name. If you look at the screenshot above, you can see that there is obviously no correct separation here.

How to rectify the error

In our tests, it was possible to encrypt emails if the syntax error of the Kerio Outlook Connector was “fixed”. This is deliberately in quotation marks, because strictly speaking we are bypassing it; the actual fix would of course have to be provided by the manufacturer of the connector.

We were able to work around the error by entering the sender address correctly. To do this, please click on the “From” field and then on “More email address…”.

Now enter your email address and confirm the entry with OK. Please omit the addition “Kerio Connector (KOC Offline Edition)” when entering.

If you now click on “Send” again, the regular REDDCRYPT dialog opens. The sender address has now been found correctly and the email can be digitally signed before sending.

If you want to encrypt an email again, please select the corrected email address again in the “From” field. This is now available for selection in the drop-down menu and you do not have to enter it manually again.

Of course, it would be better if the correct email address could be permanently stored as the sender. If you are familiar with Kerio and have a tip on how to set the email address correctly, please contact us and we will be happy to update this article accordingly.