To get something like
grep | cut you can use
sed -n s/A/B/p.
sed prints every line after all commands are processed. You can silence all output that you don't explicitly print from a command with
s command takes the form
s/$FIND/$REPLACE/$FLAGS. Specifically, the
p flag prints the line whenever a replacement is made.
With these combined, you can easily match and cut:
sed -nE "s/email2 = (.+)/\1/p" < /etc/emails.conf
In fact, this is strictly more powerful than
grep | cut because you can use an arbitrary replacement pattern.
-E option enables modern regex, which allows you to reference capture groups in the replacement pattern. For a simple cut, you can get away without it by using more clever patterns.)