Please be aware that mass emails sent from Purple Briefcase can take some time to batch up, and send out to each student individually, or they can be sent out almost immediately. This time can be longer than anticipated if the email is sent at a time where lots of other emails from your community are also being sent.
Please try to email students and employers with AT LEAST 48 hours advance notice of whatever it is that you are trying to communicate to them. For example, if you are trying to send out information to students about a particular event that is happening on a Friday, it would be best to send out that communication to them no later than Wednesday of that same week. This policy allows for emails that have been caught up in even a substantial email queue to still reach their intended targets in a timely fashion.
Purple Briefcase is continually working to improve all aspects of the platform, including email batch / send timing.