SendGrid · api · fg-0419
SendGrid rejects scheduled emails with 'Scheduling more than 72 hours in advance is forbidden'
400 Scheduling more than 72 hours in advance is forbidden
Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100
Cause
send_at must be a Unix timestamp in seconds no more than 72 hours ahead. Date.now() values are milliseconds.
Fix
Keep your own queue for anything beyond 72 hours and hand it to SendGrid inside the window, with send_at in seconds.
Apply
send_at: Math.floor(sendDate.getTime() / 1000) // only when sendDate - now <= 72h
Affects: SendGrid v3 Mail Send send_at, as of 2026-10
Sources
- https://www.twilio.com/docs/sendgrid/api-reference/mail-send/mail-send
- https://www.twilio.com/docs/sendgrid/api-reference/mail-send/errors
Have your agent know this before it fails
claude mcp add --transport http footgun https://getfootgun.com/api/mcp