What basic knowledge should one have before buying Unlimited SMTP, Webmail, Mailer, RDP ?

Reason 1: Server error: You are sending too fast

Reason 2:

Invalid Target (non-existanace emails): please validate the mailing-lists before using. If you send a-million invalid emails, the result will return to SMTP Server, the HDD will be full

Atomic Email Verifier 9.20 Order here

Message undeliverable

How to fix: >>> Please contact admin. I will delete the sent emails from the server and now You will have more space

What basic knowledge should one have before buying Unlimited SMTP, Webmail, Mailer, RDP ?