PGP Universal Server, internal users not receiving Web Messenger replies

Hi,

Currently running PGP universal server 3.3.1 in gateway placement, email is working fine and messages are being encrypted/decrypted.  I have created some external users for use with Web Messenger, they receive the message to create the passpharse and can login without any issues.  The external users can recieve  messages from an internal user fine, however when they reply to the internal user, the messgae states it has been sent although the internal user/s do not receive the message.  The log file states that the the message has been passed.

any pointers greatly appreciated.

many thanks in advance.