Hi Julian, this is not a duplicated thread. It is indeed a continuation of that threat, but as the problem has evolved so I thought I would start a new thread in order to keep the solutions seperate...
In the original thread the problem was we could not send in 'Plain text' to other PGP users at all. This was happening specifically because of a rule that was created by the consultant who installed the Universal Server for us. Disabling that rule resolved the problem of not being able to send in Plain text at all.
Now, mail is being send in Plain text by default, and the user can select manually if they want to encrypt.
But we would like new mail to be encrypted by default, and the user can select manually if they want Plain text.
Hope that clarifies it.
Thanks for your comment.