Scheduling messages
Send a message later with DeliveryDateTime, in UTC, and convert local times correctly.
Every send endpoint takes an optional delivery time. Leave it out to send now.
| Endpoint | Parameter | Time zone | Format (as documented) |
|---|---|---|---|
| REST: send a message | DeliveryDateTime | UTC | MM/DD/YYYY HH:MM:SS |
| HTTP API: send SMS | DeliveryDateTime | UTC | MM/DD/YYYY HH:MM:SS |
| HTTP API: send MMS | DeliveryDateTime | UTC | MM/DD/YYYY HH:MM:SS |
| HTTP API: send invitation | DELIVERYDATETIME | Eastern Time | for example 1/1/2014 4:00 pm |
Convert local time to UTC
Work out the UTC time in code rather than by hand: daylight saving time moves the offset twice a year.
For example, to deliver at 9:00 AM New York time on October 14, 2026 (Eastern Daylight Time, UTC−4), send:
10/14/2026 13:00:00
The same 9:00 AM on December 14, 2026 is Eastern Standard Time (UTC−5), so it is 12/14/2026 14:00:00.
from datetime import datetime, timezone
from zoneinfo import ZoneInfo
local = datetime(2026, 10, 14, 9, 0, tzinfo=ZoneInfo("America/New_York"))
print(local.astimezone(timezone.utc).strftime("%m/%d/%Y %H:%M:%S")) # 10/14/2026 13:00:00
Errors
Send MMS returns ERR:307: Invalid delivery date time. for a time it cannot read. Send invitation returns Err:722:The Delivery Date Time should be now or in the future for a time in the past.