“The Simple Mail Transfer Protocol (SMTP) is a communication protocol for electronic mail transmission. As an Internet standard, SMTP was first defined in 1982 by RFC 821, and updated in 2008 by RFC 5321 to Extended SMTP additions, which is the protocol variety in widespread use today”.
WIKI
CB-Form builder pro sets [email protected] as default sender email. But you can set your own sender (eg. [email protected]) with SMTP configuration here.
If you have an SMTP service, you can check their guidance for SMTP credentials (google “{your provider} + SMTP credentials”). You are fresher at SMTP, you can register a free plan account at sendgrid.com. (SendGrid’s guidance).
You can follow these steps in this screenshot to setup SMTP with SendGrid
