Recently some friends of mine using Hotmail accounts complained that I was no longer writing them, or replying to their mails. I checked my mail server logs, and found nothing. At my "home office" I have an ADSL router and I got a fixed IP address. This allows me to run some services (FTP, CVS, etc. ) to access some data while working remotely, and a mail server I setup years ago to keep spam and viruses under control, and use my own domain mail addresses.
I started to trace the connection to Hotmail, and found nothing wrong. Hotmail accepts the message, but it is never delivered.