I don't think it's to do with being logged in or not. The URL you want to send seems to be http:// www.eastdulwichforum.co.uk/forum/read.php?30,812227 . What is actually sent shows up as http:// www.eastdulwichforum.co.uk/forum/read.php?30%2C812227 in the page source. The %2C is a valid encoding of a comma, but it appears to be causing difficulties for some software. I wouldn't sweat over the cause but just try resending the comma version. In both cases above I've put a space after the http:// , so that this forum's parser will display the full text here rather than making a link of it. Take the space out, of course, to send it. You should be able to test the link in your out tray. In any case, browsers should be able to manage without the http:// , though any software displaying it without probably won't treat it as a clickable link. Grisly details of URL encoding here for them as wants: http://en.wikipedia.org/wiki/Percent-encoding