Determined how to tell if an email address is valid or not without sending one to it.
read more figureOutIfEmailIsValid.sh
#How to check if email is valid
#Note: this varies on a couple factors, including
#1. sometimes the mailserver will just be mean and not divulge any info
#2. sometimes your ISP might be blocking telnet connections, so you should tether
#this does work with Gmail, amazingly. Zoho too. Seems like others, like unc.edu block you.
#First,
#figure out their mail servers, by running
nslookup -q=mx [domain].com
#This will list something like mx.zoho.com, telnet to it on port 25
#if telnet isn't available can use line below
telnet mx.zoho.com 25
#OR
nc mx.zoho.com 25
#this will start a session, which is essentially a sending email session
helo hi
#it will respond with a greeting
mail from:
#it will respond with OK
rcpt to:
#it will respond with an error most likely if it doesn't exist, just try an address you know exists
quit
#ends session