I know that to send an e-mail from an SMTP server, one needs a server address, password and username/default credentials. But, does SMTP also have a password to access the server itself ? Is there a username as well ?
All you need is
You do not need a password to the "server itself" or anything like that.
Depending on the server config, the email you send "from" may or may not need to be a valid email address on that server.
EDIT: basic C# implementation
System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(); message.To.Add("email@example.com"); message.Subject = "This is the Subject line"; message.From = new System.Net.Mail.MailAddress("firstname.lastname@example.org",25); message.Body = "This is the message body"; System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient("yoursmtphost"); // if you need user/pass login client.Credentials = new NetworkCredential("username","password"); smtp.Send(message);