I have this error when answering emails from ox guard reader:

---An error occurred during sending the encrypted email reply.---

I have correctly configured file lines: guard-core.properties

# Specify the SMTP server information for replies of external recipients. Those recipients
# are able to decrypt, display and reply to eMails they receive via the link to the Guard
# reader in those encrypted eMails.
# The SMTP server is also used for sending password reset emails

# Emails with new passwords are sent to internal ox users when they have a new email
# sent to them. These password emails are used for password reset, and when a new
# key is generated for a user. This can be configured through the senders configuration
# cascade, but should be sent here for system email address
com.openexchange.guard.passwordFromName=First Last

any idea what may be wrong?

sorry for my English