In order to prevent our mail servers from being identified as spam and distrupting services, ESA emails max out at 25 recipients.
While this should be sufficient in most cases, there's a few cases in which this won't be enough - messages for the whole school, to all customers, etc. In these cases, there's a workaround which lets you send email to everyone you need to reach:
1: Log in to ESA as an administrator.
2: Click Create User in the top left of the interface.
3: Select Alias from the drop down on the right.
4: Enter a Username explaining the account you're about to create (a whole class/ year group for schools, employees/ customers for companies, for example).
5: Add all the addresses you want to send mail to in the Copy Mail to section. You can add internal addresses via the drop down menu, or write in external addresses below.
6: Click Submit, and the account will be created, letting you quickly send mail to everyone included in the alias.
7: When you're sending emails to multiple recipients in this way, we recommend only using the alias in a BCC, so the address can't be misused. Use your email address (or a relevant internal one) in the To field.