Some ISP’s may block SMTP port 25. If your ISP does, then you will need to use your ISPs outgoing mail server for configuring your outbound SMTP for your email account.
Here is a list of some Australian ISPs and their corresponding outgoing mail servers.
| AAPT | mail.aapt.net.au |
| Bigpond | mail.bigpond.com |
| Dodo | smtp.dodo.com.au |
| iiNet | mail.iinet.net.au |
| Internode | mail.internode.on.net |
| iPrimus | smtp.iprimus.com.au |
| OntheNet | mail.onthenet.com.au |
| Optusnet | mail.optusnet.com.au |
| Ozemail | smtp.ozemail.com.au |
| Three (Mobile) | smtp.three.com.au |
| TPG | mail.tpg.com.au |
| Virgin (Mobile) | smtp.virginbroadband.com.au |
| Vodafone (Mobile) | smtp.vodafone.net.au |