basically i have to run in cmd.exe the following commands on C#(if you run it on CMD, it'll work) this link explains better
nslookup -type=mx emailProvider.com //for exemplo nslookup -type=mx hotmail.com.com
after it retun this:
Server: ip-172-31-0-2.sa-east-1.compute.internal
Address: 172.31.0.2
Non-authoritative answer:
hotmail.com MX preference = 5, mail exchanger = mx1.hotmail.com
hotmail.com MX preference = 5, mail exchanger = mx2.hotmail.com
hotmail.com MX preference = 5, mail exchanger = mx3.hotmail.com
hotmail.com MX preference = 5, mail exchanger = mx4.hotmail.com
so I take some mail exchanger, for exemplo:
telnet mx1.hotmail.com 25 //port 25
after I nedd write "HELO" for exemplo:
HELO
so finilly I write :
mail from:<michele@sacapp.net>
rcpt to:<michele_labriola@hotmail.com>//email verificate
so it return a number, 250 or 550, if 250 the email don't exist, else it exists
I tried use the minimalistic Tel net , I tried Process to write lines command windows but nothing of this working, it just work before helo, when I write helo it's don't work but it's working on CMD
some on can help me please?
sorry for my bad english
Thank you!
Good question, POOR solution.
You are attempting to query the SMTP server to see if an email exists. I highly recommend you don't do this, because your external IP address will end up on a blacklist and you'll be unable to send any mail!
You don't need to call an external telnet process to communicate with a SMTP server. You can use a TcpClient instance. Examples: this, and this.