I have a similar problem. email works on a g4, but not on either two imacs on my local network. also talked with everyone possible, brighthouse, apple, etc. no answers. mail works to and from my isp, but nothing else with the imacs. My hunch is wireless network conenctions has something to do with it or I may have a problem running panther on the g4 and tiger on the imacs. they have programs that find "conflicts" like conflict catcher and system check, and others. About to try resetting entire system because the email worked for a while on both imacs and then stopped. Not sure how this relates to iphone, but resetting to your originals factory settings may help, if you can. Add on and plug ins added after use may cause conflicts within the system, corrupting files which may be in use when your problem occurs. good luck.