Quoting Doug McGarrett
I don't know if this is related or not, but as of last nite, I cannot send a message to anyone@aol.com from Linux 9.2 KMail. I can send thru other servers, but something at aol blocks the mail and gives me some kind of message about wrong protocol, or something. (Can't reproduce it now, I had to go to Windows to contact some folks who have the aol mail.) I have been told that Macintosh users can have similar problems trying to email to aol users. I called aol and they admit to nothing. I called my isp and they know nothing, including Linux.
AOL does not accept SMTP connections from dynamic IP addresses, you have to forward thru your ISP's SMTP server. But this has been true for months. They may have just added more ranges. Initially they blocked dialup IP addresses. About 2 weeks later they added cable addresses. HTH, Jeffrey