My company has our email hosted through another company. We use Outlook Express to access our email, though the email host does also provide web access.
Prior to Monday, 3/12/2007, all of our emails were being sent and received without a problem. During the weekend of 3/9/2007 to 3/11/2007, our email host updated something on their end (they sent a notice out saying they were going to do this). I'm not really sure what they did, but now we have a different interface when we access our email through the web site, and I'm pretty sure they beefed up their junk email filter too.
Anyway, beginging on 3/12/2007, we now have certain problems with our email. Emails without attachments go through fine, but we experienced emails with certain attachments would not go through. I narrowed it down to only emails that have a ZIP file attached which contained a file with the CBK extension will not go through. Weird thing is, if I were to send a CBK file directly attached to the email instead of zipped, it will go through fine. Only when it's inside of a ZIP file does it not go through. ZIP files that do not have a CBK file in them come through fine.
Another weird thing...sometimes these types of emails that aren't coming through, will come through, but 99% of the time they don't.
So I called our email host, and they told us that they don't see any emails not coming through. I've been on the phone with them every day for over a week, and they swear the problem is not on their end.
Now everyone that is experiencing this problem works at different locations. It's not any one computer or any one Internet connection that is having this problem. But for the life of me, I can't figure out why these emails aren't going through. If our email host isn't seeing these emails being directed somewhere else, then the emails aren't even getting that far. What else could be the problem? Please, someone help!