Endpoint Encryption

I edited the Opportunistic Encryption policy to Clear-sign message for when the recipient's key is not available, and my client saw those icons in the sent folder and is asking me to remove it. I would like to know what it means so I can explain why she needs that.

Thanks,

here is the picture.

If the icon is the result of your clearsigning the email, it would seem the only thing you can do on your end is not clear sign messages to that client.  You can create a new PGP messaging policy to accomplish this (placing it above your Opportunistic Policy):

If any
Recipient is your-client's-email-address
Send in Clear

What is the benefit of clearsigning an email?

Clearsigning is the old way of signing email before PGP/MIME started being used.  I don't think there is a lot of benefit to it.  However, it may be more compatible with some very old PGP software (such as version 2.6.2).  Some people may prefer to use clearsigning so that people without PGP will see it and ask about PGP use as a result; but a negative consequence of this is that non-PGP users tend to be annoyed by it.  The other possible benefit I can see is that clearsigned PGP messages probably remain with the signature and the signature could therefore be re-verified at a future date. 

Thanks a lot !

You are very welcome.