Help for newbie with epals

I have just signed my class up for schoolmail with epals.  I have made accounts for each of my students.  I have been trying unsuccessfully to email a message to one of my students as a test and my email messages are bounced back to  me as undeliverable.  The message I receive says the recipient is only able to receive email messages from within epals.  We want to exchange email messages with a class that does not use epals.  I cannot find any filtering settings on my account to allow email messages from the internet.  I am the only teacher I know trying to use epals.  Can anyone help me with this???

Thank you so much.

Rhonda