#!/usr/bin/perl

while (<>) {                   # take one input line at a time
    chomp;
    if (/(dmathis@gmail.\w+)/) {
        print "Matched: |$`<$&>$'|\n";  # the special match vars
    } else {
        print "No match: |$_|\n";
    }
}

##</code><code>##

I am using dbmathis@domain.com with this example?
No match: |I am using dbmathis@domain.com with this example?|
I am using dmathis@gmail.org this time.
Matched: |I am using <dmathis@gmail>.org this time.|