there are no errors showing, however, have SOLVED it.
smtp_sasl_auth_enable = yes
This doesn’t need to be enabled unless you’re using a relay. Try changing that to:
smtp_sasl_auth_enable = no
during this process I had tried setting this to yes due to “Use SSL for SMTP? NO”
as I had thought it needed to be set (as it was on other server)
emails are now sent - phew!
thanks everybody for your help.
my fault in some simple mistakes