gmail.com hides the IP address of the originator of the e-mail. Because of this, spammers can use gmail to hide their origins.
We consider this policy unacceptable, and therefore refuse to accept mail from gmail.com.
We realize that gmail is a convenient free e-mail provider. If you wish to use a free e-mail account to send us mail, please consider one of these alternatives:
Alternatively, if you wish to continue using gmail, please suggest to Google that they stop hiding the origin of their e-mail messages.
Google claims to hide the IP address to protect people's privacy. We do not accept this; every other free mail provider reveals IP addresses with no issues. And Google only hides the IP address of senders who send via HTTP. If you send mail through Google using authenticated SMTP, your IP address is revealed. Why is there a privacy concern for port 443, but no privacy concern for port 25?