SMTP

How to test SMTP Authentication and StartTLS

When investigating SMTP authentication issues, particular over TLS encrypted SMTP connections, it’s always handy if you are able to test the SMTP authentication and StartTLS connection. Preferably from your command line. This post shows you how to test SMTP servers, verify SMTP authentication and StartTLS encrypted connections from the Linux and Windows command line.

Add (custom) headers to MailMessage class

How to add custom headers to System.Net.Mail? When sending an email using the MailMessage class (System.Net.Mail namespace) in an ASP.NET website, certain email headers like Message-ID are not always set. When a Message-ID header is missing, email might be blocked by the recipients SMTP server. Therefore it is necessary to set such headers…

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