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

IP Server blacklist check:

BUT Spamhaus: Clear

If you only use SMTP to spam domain mail, yahoo & aol. You should use it.

Standard of Normal SMTP

Because of private server was not registered with major anti-spam organizations. Unlimited SMTP cannot send inbox to popular email providers like: Gmail, AOL, Outlook, Yahoo...etc

Test Deliver ( Plain Text ):

Title & Messenger: Best Good For You.

+ Yahoo, Aol ( Spam )

+ Yandex ( Inbox, Spam or Not deliver )

+ Domain mail don't have a system to filter mail, fight spam, Block ads, Block phishing mails: Inbox

   Company Emails ( Domain mail ) created from the company server. They don't have a system to filter mail

+ Domain mail have a system to filter mail, fight spam, Block ads, Block phishing mails: Inbox or Spam or Not Deliver (
   ex: hosting provider: GoDaddy,Hostgator ... etc ) There are many companies buying server or hosting from providers. They
   also have a system to filter mail. Their email filtering system is weak. So you should buy DKIM, SPF Unlimited SMTP or
   Webmail to pass. if SMTP don't pass -- Not Deliver

This 's video & demo:

Unlimited IP SMTP or Unlimited Domain SMTP ( Normail SMTP )

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