Z10 will not send to direct email address - seems MUST be in contacts list ?
Just been sending from to an account that I did not send to before, entered the email address, and it failed (RED No Entry sign), no explaination of error - just failed and try later.
after several re-tries, tried a new message to an existing email, which matched a contact list entry. It went OK (what ? why is it suddenly OK ?).
So deliberately created a new contact for the pure email address, edited the old (wont send) email, deleted address, entered again - it matched the contact and displayed that name. Send, and it worked !!!
That is a completely undocumented and unneccesary restriction.
Get rid of it now.
Meanwhile, you HAVE to give ERROR messages details - not "Can't send now' - when it clearly is not true either.
(even if it is my Mail provider - because you are not formatting correcttly, I still want to see details - so I know it is me not the Z10 restricting the send)