I was trying to use the email option after running a condor job. I tried this:

Executable   = executable.sh
Log          = file.log
Output       = file.stdout
Error        = file.stderr
# Use this to make sure 1 gpu is available. The key words are case insensitive. 
REquest_gpus = 1
# Note: to use multiple CPUs instead of the default (one CPU), use request_cpus as well
Request_cpus = 3
# "Queue" means add the setup until this line to the queue.
Queue
#
Notify_user = my_email@yahoo.com

but it failed. Why? How do I put it in the submission file?

This didn't help either:

notify_user = $<$email-address$>$
Used to specify the e-mail address to use when Condor sends e-mail about a job. If not specified, Condor defaults to using the e-mail address defined by
job-owner@UID_DOMAIN
where the configuration variable UID_DOMAIN is specified by the Condor site administrator. If UID_DOMAIN has not been specified, Condor sends the e-mail to:
job-owner@submit-machine-name

https://research.cs.wisc.edu/htcondor/manual/v7.6/condor_submit.html

regardless I want it in the job.sub script regardless.

Edit:

I put the notify user at the end. Now I do not see errors in the condor logs but I am not receiving an e-mail. So it means condor parsed my filed correctly after having Queue be at the end but it's not sending emails. Anyone know why?

In an HTCondor submit file, the "Queue" statement should also be the last thing in the file. Try moving the Queue to the end, so that the notify_user is somewhere before it in the file.

Also, you'll want a notification = always in the submit file, like this

 notify_user = my_email@example.com
 notification = always