PHP cant access smtp under iis7

[webaus]

We have a weird issue where PHP scripts work fine with sendmail under iis7 but scripts using smtp wont connect to the smtp server with or without smtp authentication

Im at a loss to explain why and am not sure if somethings been missed in the serup of the server

anyone aware of what needs to be done to get smtp working for submissions by php scripts on the server?

php.ini has smtp enabled on port 25