Simple Mail Transfer Protocol Smtp. Smtp simple mail transfer protocol is the basic standard that mail servers use to send email to one another across the internet. Smtp is also generally used to send messages from a mail client to a mail server in host.
Smtp is a push protocol and is used to send the mail whereas pop post office protocol or imap internet message access protocol are used to retrieve those emails at the receivers side. Smtp simple mail transfer protocol is a tcpip protocol used in sending and receiving e mail. Smtp stands for a simple mail transfer protocol.
Nmap and smtp user enum tools are able to enumerate the simple mail transfer protocol server but you have knowledge about the correct command.
All information available in your linux os just needs to figure out the correct pathway. An smtp port is a combination of both. Appendices a b c and d describe the use of smtp with various transport services. All information available in your linux os just needs to figure out the correct pathway.