Emails Format issue when sent out from Dynamics 365

I have some automated emails generated(via workflow) and sent out from CRM.

When any email is generated( via workflow), user if adds any text to it, emails are sent out in different fonts and styles.

Is there any way to control this formatting to what the existing email has, when user tries to add new wordings?

Also few automated email also go in different fonts sometimes even though user doesn't change anything . 

Thanks,

P