Has anyone ever tried sending emails using 1&1 smtp host? I tried the following?
SmtpClient mailClient = new SmtpClient("smtp.1and1.com", 587);
mailClient.Credentials = new NetworkCredential("admin@permias-tucson.com", "password");
But it always gives me a security exemption error...
I tried it using my local host and it works fine.. I tried using gmail's smtp and it worked fine as well.. It says that I need to authenticate in order to use the smtp server, I did that by looking at the code above... Here's the exact error:
Security Exception
Description: The application attempted to perform an operation not allowed by the security policy. To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.
Exception Details: System.Security.SecurityException: Request for the permission of type 'System.Net.Mail.SmtpPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
You need to authenticate to send SMTP mail (Point 2a from their FAQ)
My client has a new hosting from 1and1.com, and the thing that worked for me was to remove the port number and it working. 1and1 provided me a reference link http://help.1and1.com/hosting-c37630/scripts-and-programming-languages-c85099/aspnet-c39624/send-an-e-mail-using-aspnet-a604246.html
My code:
SmtpClient objSmtp = new SmtpClient("smtp.1and1.com");
objSmtp.EnableSsl = true;
objSmtp.Credentials = new
System.Net.NetworkCredential("mail@email.org", "PWD");
also just ensure that your reverse (PTR) maps back to you... otherwise alot of SMTP servers will reject you.
来源：https://stackoverflow.com/questions/2623585/11-web-hosting-and-smtp-configuration