In Reply to: outgoing email server posted by Bintang girl on Tuesday, 14. October 2014 at 08:57 Bali Time:
Same thing happened to me last year, could receive emails on the iPad using our villas wifi, but not send any. I had to log into my Telstra account and go to their Webmail where I could then send replies.
Optus would have their equivalent to Telstra's webmail so try logging into your Optus account and go from there. It won't make any difference to change your sim provider so leave in what you have got. Cheers.