{"id":220,"date":"2010-05-13T22:23:39","date_gmt":"2010-05-13T21:23:39","guid":{"rendered":"http:\/\/www.penguino.co.uk\/?p=220"},"modified":"2011-06-14T18:30:39","modified_gmt":"2011-06-14T17:30:39","slug":"o2-broadband-cannot-sent-outbound-email-to-external-smtp-server-via-port-25","status":"publish","type":"post","link":"http:\/\/www.penguino.co.uk\/computing\/o2-broadband-cannot-sent-outbound-email-to-external-smtp-server-via-port-25","title":{"rendered":"O2 broadband – cannot sent outbound email to external SMTP server via port 25"},"content":{"rendered":"\n\n\r\n\n\n\n

I was helping a friend who has recently installed O2 (UK) broadband at his premises.<\/p>\n

\"O2<\/p>\n

He was using Microsoft Outlook and the first thing he noticed was that – he was unable to send\/relay emails via his own SMTP server setting, although his incoming emails were unaffected.<\/p>\n

My initial diagnostic on his PC, was to check his\u00a0outgoing port 25 access to various external smtp servers, as expected, I was unable to connect to any.<\/p>\n

I went through his PC’s firewall settings, antivirus and spam filter settings, and even I investigated\u00a0the router’s firewall configuration.<\/p>\n

After almost an hour,\u00a0I could not find the reason why\u00a0the outgoing smtp connections were denied – until….. thanks to David Nicoll’s blog, I’ve found the answer.<\/p>\n

[Link is now dead but read on\u00a0http:\/\/blog.davenicoll.com\/2008\/10\/29\/cant-send-email-on-o2-broadband\/]<\/del><\/p>\n

In essence: O2 broadband\u00a0blocks all outgoing port 25 SMTP connection<\/strong> UNLESS you are using O2’s own mailserver, and relaying mail through their server.<\/p>\n

Luckily for my friend, he is using Spam Arrest’s SMTP server – which allows connection from an alternative port and thus by-passed O2’s restriction<\/p>\n

http:\/\/www.spamarrest.com\/support\/client\/<\/a><\/p>\n

(I am not trying to advertise for Spam Arrest – just please note that you do need to be a paid user to use spam arrest’s smtp server for sending\u00a0outgoing mail)<\/p>\n

I hope this will help some new O2 broadband users looking for a solution.<\/p>\n