We recently upgraded to JIRA 5.0 from 4.1. After doing this we noticed that when someone creates/updates an issue, JIRA sends out the notification emails one at a time in intervals of about 15 seconds. We did nothing different when setting up 5.0 with mail handlers and the SMTP mail server settings. We did migrate at this time to a new exchange server. We have tried many things to JIRA to send out the emails in bulk but nothing is working. Any help would be appreciated.