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Do SMTP servers require that the sender in an email be the authenticated account? Or is this something that can be configured on the server?

To test out my application, I've set up a Gmail account to use Gmail's SMTP servers, which require me to authenticate with the Gmail account before sending email. Gmail's SMTP requires that the sender in the generated email always be the authenticated Gmail account. However, in a production environment, this application will likely deployed on a corporate network.

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up vote 2 down vote accepted

There's no technical or legal requirement that a user be authenticated, but most email servers are configured to require authentication when sending email.

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+1 Almost all servers on the net require a session to authenticate before accepting email for relay (mail being sent to another server). It's also common that once a session is authenticated the server does not verify that the authenticating account has "access" the the from: field (ie, many servers will accept Alice's credentials to authenticate the session, but will then allow the session to send mail as "From: Bob"). There are severs however that verify this by default, but it's not common when you limit your scope to the SMTP protocol. Rarely, An "Open Relay" does not require auth. – Chris S Nov 10 '10 at 1:33

No. Most will however so that they are not used as an open relay.

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+1 for understanding the difference between sending email and relaying email. The former does not always require authentication; the later almost always does. – james.garriss Jan 17 '13 at 12:26

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