Our non profit Website was built on here by a former associate who is no longer with us. I have access to the website but not webmail

As the title says, I have access the website and have updated the contact buttons to send to the proper email addresses. The problem is that I don't have access to the webmail that sends those emails and I'm not receiving emails when I do a test. another problem is that the former associate that built the site is a jerk and he will not help. 

  Is there a way to fix this issue on my end? 

Thanks is advance for any help!