Gmail
Gmail 550 5.2.1 — account inactive, or receiving mail too fast
550 5.2.1
Gmail documents two versions of 550 5.2.1. "The email account that you tried to reach is inactive" means the recipient's Google account isn't in use, so mail to it is refused. "The user you are trying to contact is receiving email at a rate that prevents additional messages from being delivered" means that one recipient is getting so much mail that Gmail won't accept more for now. The first is about a dead address; the second is about volume to one recipient.
How to fix it
- 1
"The email account that you tried to reach is inactive"
Suppress the address on mailing lists, like any hard bounce. Google can disable and eventually delete personal accounts that stay unused for a long time, so the address may never work again. For a contact you need, reach them another way.
- 2
"receiving email at a rate that prevents additional messages"
Something is sending this one recipient a very large amount of mail. If it's you, for example alerts, notifications or a loop between systems, slow down, batch notifications into digests, and look for a forwarding or auto-reply loop.
- 3
If you're the recipient getting flooded
Find the source of the flood in your inbox: a misconfigured alert, a mailing list loop, or a subscription bombing attack. Filters won't stop the rate limit, but stopping the source will.
Meaning current as of 2026-10-24, cross-checked against the provider's own documentation. Providers do occasionally redefine codes — if this doesn't match what you're seeing, the source link is the authoritative reference.