Level: Intermediate
Any domain sending 5,000 or more messages per day to Gmail or Yahoo addresses is classified as a bulk sender and held to a specific, enforced set of technical requirements.
The Threshold Is Permanent Once Crossed
Once a sending domain crosses the 5,000-per-day threshold to a given provider, bulk sender requirements apply going forward indefinitely, even if volume later drops below that level.
Requirements Cover Authentication, Complaints, and Unsubscribe
Bulk senders must have properly aligned SPF, DKIM, and DMARC, keep spam complaint rates below defined thresholds, and support one-click unsubscribe on marketing mail.
Non-Compliance Now Results in Outright Rejection
Rather than simply routing non-compliant bulk mail to spam, major providers now reject it outright at the SMTP level with a permanent failure response, making compliance a hard requirement rather than a best practice.
Next step: Use the Find DNS Records to check your domain's current authentication setup against the bulk sender requirements before you cross the volume threshold.