Email tools, Trace Email, Spamassassin check, Relay test
Can I determine the IP address of the sender of an email?
*NEW - Now you can trace email sender from facebook!
Check your spam score on your newsletters.
Check if your mail server is correctly configured for signing outgoing mails with DKIM and DomainKeys. Check if you have correctly configured Sender ID and SPF records in DNS for your domain.
An open relay is a smtp server configured in such a way that is allows a third party to relay (send / receive email messages that are neither from nor for local users). Therefore, such servers are usually targets for spam senders.
Sender Policy Framework (SPF) is an attempt to control forged e-mail. SPF is not directly about stopping spam ? junk email. It is about giving domain owners a way to say which mail sources are legitimate for their domain and which ones aren't. While not all spam is forged, virtually all forgeries are spam. SPF is not anti-spam in the same way that flour is not food: it is part of the solution.