Email tools, Trace Email, Spamassassin check, Relay test
Can I determine the IP address of the sender of an email?
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Check your spam score on your newsletters.
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.