Change formatting of custom property in email

I’m wondering if it is possible to change the custom property that’s input for deal follow-up emails. I am trying to use it to create an email address by using a salesperson’s name and adding ‘@mycompany’ at the end of the HTML insert for it. 

It currently looks like this:

<p>
{% for sales_rep in deal.sales_rep %}
{{ sales_rep }}@mycompany.com
{% endfor %}
</p>

I am able to get the name to show up but it appears as ‘John Doe@mycompany.com’ instead of ‘JohnDoe@mycompany.com’ is there any way to fix this? 

Could I possibly add a formatting conditional to an inserted token on the email to achieve the same result?