have a bit of an odd problem with MobileMe email in that sometimes emails to one particular email address bounce back undelivered with 'Illegal host/domain name found'. The email address is a perfectly valid one, and sometimes the emails sent from my iPhone are delivered fine. I never have a problem sending to this email from my Mac, although this uses a different SMTP account than the MobileMe one which makes me think the problem is with MobileMe. Here's the full error message for an email I sent to two email addresses, firstname.lastname@example.org being the problem one and email@example.com being a different one (though both recipient email addresses are hosted on the same server). The message to xxxxxx bounced but the yyyyyy one was delivered fine. Your message cannot be delivered to the following recipients: Recipient address: firstname.lastname@example.org Reason: Illegal host/domain name found Original-envelope-id: 0LIC0036DUVGMK40@asmtp029.mac.com Reporting-MTA: dns;asmtp029-bge351000.mac.com (tcp-daemon) Arrival-date: Sun, 20 Mar 2011 05:04:29 -0700 (PDT) Original-recipient: rfc822;email@example.com Final-recipient: rfc822;firstname.lastname@example.org Action: failed Status: 5.4.4 (Illegal host/domain name found) From: N---- J---- <----@me.com> Date: 20 March 2011 12:04:24 GMT To: P---- J---- <email@example.com>, S---- J---- <firstname.lastname@example.org> Subject: Hi! Any ideas greatly appreciated!