I have a client running SBS 2003 with all updates applied. Their connection is DSL with a static IP. I have run https://www.testexchangeconnectivity.com/ and everything checks OK. The clients IPhone has no problem sending mail. Only some of his email gets to the phone. He can never get more than one email at a time. If there are multiple emails for the phone he only sees the first one and the others never make it. Sometimes he gets no email at all and then will get mail that is a day or more old. OWA is never a problem. The phone is a 4S running OS 5.0.1. There are other employees with Motorola phones that also have problems receiving mail but no problems sending.