Email(toEmailAddress, fromEmailAddress, subject, body, fileName);

I use SmtpClient class to send emails. The hard coded sender's address is donotreply@somedomain.com.

I have run some tests with different "TO" email addresses. Emails sent to my hotmail, and Gmail are never sent to my company's email address even to junks. Neither is our client's email address.

What is the requirement of sending emails that will not be blocked by spam filters?