If your event has been postponed, here's the best way to handle it within Sessionize.
Change the event date
Visit the Event tab on the Edit event page and change the event's date to an appropriate new date.
Create an event-wide alert
Visit the Advanced settings tab on the Edit event page and write an event-wide alert in the appropriate field. Click Save changes to confirm. The alert will be visible on your event's Call for Speakers page, directly below the logo, and it will be visible to speakers in their speaker dashboards. Mention the event's new date in the alert.
Edit the Call for Speakers date
Visit the Call for Speakers tab of the Edit event page and edit the Call for Speakers date to whatever you find suitable. You can either prolonge it or temporarily close it, by selecting a past date in the CfS open field. Confirm your selection by clicking Save changes.have
If you happen to have speakers whose sessions you have already accepted, contact them through a group mailing message to tell them about the new event date(s). Such messages are created on the Group mailing page.