True. When we launched our email service, the only users we had complaints from about emails not being delivered, were hotmail users. As it turns out, Microsoft's SMTP servers were simply dropping all messages from our servers, without giving us an error code - they would respond with "Message is accepted for delivery" and silently discard it.
As it turns out, we had to custom-register our SMTP server with hotmail administrators. It took us about 20 emails back-and-fro and about two weeks, but they finally started accepting our messages.
Not only this violates SMTP standard, it also demonstrates their "f'ck you all, Internet" attitude: they are saving on spam filtering at expense of everybody else: their users, our users, etc.
As it turns out, we had to custom-register our SMTP server with hotmail administrators. It took us about 20 emails back-and-fro and about two weeks, but they finally started accepting our messages.
Not only this violates SMTP standard, it also demonstrates their "f'ck you all, Internet" attitude: they are saving on spam filtering at expense of everybody else: their users, our users, etc.