Getting SmtpClient to work with a self signed SSL certificate

c# ssl smtpclient self-signed
sipsorcery picture sipsorcery · Jan 28, 2010 · Viewed 17k times · Source

I'm attempting to use the System.Net.Mail.SmtpClient class to relay an email through my company's email server. All SMTP connections to the mail server have to be SSL and it uses a self signed certificate. That's fine for Outlook where you can just click ok on the warning dialogue but does anyone know a way to get SmtpClient to accept a self signed certificate?

I'm planning on using this app on the Windows Azure Platform so I won't be able to install the self signed certificate as a trusted root.

Answer

Darin Dimitrov picture Darin Dimitrov · Jan 28, 2010

You may take a look at the ServerCertificateValidationCallback property:

ServicePointManager.ServerCertificateValidationCallback = 
    (sender, certificate, chain, sslPolicyErrors) => true;

It represents a callback which is called by the runtime when it tries to validate an SSL certificate. By returning true you basically say that you don't care if the certificate is valid or not -> you always accept it. Of course having self signed certificates in production environment is not a good idea.

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