Being a user on more than one account

Being a user on more than one account

I have my clients use Zoho CRM for their databases. I do a lot of work on their databases and need to have access to them using my e-mail address so that when they assign a task they can have an e-mail notification sent to me. I have found that I can only use my e-mail address on one account because it is used as the User ID. Any suggestions as to how I can get around that?Thank you in advance.
Lindsey Kauffman