Pulling my hair out so thought I would reach out to you clever folk. I have Windows Server 2003 and IIS6. I send email from sites using ASPEmail for contact forms etc (connecting to mail host via the ip address), but increasingly I am receiving the error "550 Access denied - Invalid HELO name" and the mail being rejected. I understand if each site is on a different IP Address I can set the reverse domain lookup for the IP to match the sending email address, which solves the problem. However, smaller sites share an IP address, and here I am stumped. I keep thinking there must be a way under MMC and IIS to set something under the Virtual SMTP server, but don't know what. Help!! Any help much appreciated..