unable to connect to your outgoing (SMTP) e-mail server

I have been banging my head against the wall lately, trying to send emails through my outlook.

Whatever SMTP account I was using, I would always get the same error message: unable to connect to your outgoing (SMTP) e-mail server

And googling this error didn't help much. Most of the post were related to firewall settings.

My issue was slightly different: I have recently subscribed to 02 broadband, and was having this issue whenever I was using their wireless router. I disabled their firewall, nothing changed.

A quick call to their customer service department (which is excellent by the way) gave me the answer: O2 prevents access to any SMTP server except their own SMTP server!

and there is no way around it - if you need to send emails through SMTP, you need to use your O2 account. the only other alternative is to order a static IP address.

O2 is not the only ISP preventing people from connecting to other SMTP servers. I had the same issue with Wanadoo for instance in France.

The reason they give is that they want avoid spammers using their network for sending forged emails. But by doing so, they also create a lot of headaches for people like me, who spend hours trying to figure out why they cannot sent emails from their email client any more!

I must say that their customer service has been very useful though. They took my concern very seriously, understood the point I was making, and promised to follow up.
And for this reason alone, I will definitely stay with them. And I would still recommend using them as ISP, hoping that they will address this issue swiftly!

And in the meantime, hope that this post will avoid other users from wasting hours trying to figure out why they cannot send emails!