Failed to Unlock Signing Key [0xa1010009]
I have this nasty error message returned as an email after the original email is sent:
Your message did not reach some or all of the intended recipients.
Subject: RE: Settlement Information Form 004
Sent: 12/30/2012 2:55:00 PM
PGP: Message is blocked - failed to unlock signing key. Error code: [0xa1010009].
The original message is embedded in this non-delivery report. Click Send Again to see the original text and have the opportunity to re-send the message. If the problem persists and you still receive another non-delivery report, please contact your administrator for details.
It happened with two users, so I checked what's special about them. I found both of them have expired keys (in addidion to the current ones). What do I do about this?
Many thanks in advance!