Andrew,  Quota notifications currently only support 1 e-mail address.  Being able to enter it in the WebUI is a bug.  I can reproduce this bug in my environment so I'll file a bug on this.  There are a few ways to get around this.  None of them very elegant.  The first is to use an e-mail alias as the destination.  The second is to have the quota trigger an event and put multiple e-mail addresses in the event trap.  Using this latter method however means those e-mails may get a lot of quota alerts.
How can I enter multiple email addresses while:  isi quota quotas notifications create --action-email-address ???  I have attempted multiple different formats, and it either complains that it is not a valid email address or it claims I have multiple values which is what I want to do.  It is possible to enter multiple address through the OneFS GUI, but I am attempting to script the process.  Thanks 
How can I enter multiple email addresses?