You do not have a PGP key for the following recipient

Dear Reader,

We are using PGP Universal + BES 5.0.4 + PGP Support Package

I want to send encrypted emails to a recipient but I recieve the following message;

            You do not have a PGP key for the following recipient: user@domain.com

            With the following options:   Do not send - Remove from message - Send to server

I do not have any problem to send/receive encrypted emails to recipients in our own a PGP Universal organisation.

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I have found the following message but was unable to find any option to resolve this issue;
http://www.symantec.com/business/support/index?page=content&id=TECH186091

Also I had found the following post, but no solution had been posted.

https://www-secure.symantec.com/connect/forums/pgp-support-package-blackberry-you-do-not-have-pgp-key

Can anyone give me advise / solution for this problem?