Sending Thousands of Email per day without being spam

Sending Thousands of Email per day without being spam

I'm having a website developed with ASP.NET which is a online art
competition,that people can register and enroll with competition. In my
system there are lot of emails that sends on various stages of the process
for a user.
as an example one user gets.
1.Account confirmation email 2.Welcome email 3.Competition Instruction
email 4.Password reset email 5.Payment confirmation email 6.Thank you
email for completing the enrollment process.
like wise i need to send various emails.So now the number of users
registering per day is getting higher and higher. So lets say there are
more than 2000 - 5000. So there will be more than 10000 email sending from
my noreply@mydomain.com email im using to send emails. Anyway one email
message only send for a one user. Meaning there is only one user email
address in 'To:' field and no 'CC:','Bcc:' fields. My question is is this
considered as spamming ? I have a doubt that my email can be marked as
spam.How i can avoid this? Is there any way to do it properly ? Anyone out
there who experienced with this matter please help me out. Thank you