Will Gmail accept your mail?
Gmail asks every sender for SPF or DKIM. From 5,000 messages a day it asks for both, and a DMARC record. Type a domain to see which level it reaches.
Who holds the name, its DNS, its mail and its website.
About fifteen seconds
The names that copy yours, and which of them are registered.
Counted at once
The DMARC policy, the SPF record to the end, and the DKIM keys.
A few seconds
Whether Gmail, Yahoo and Microsoft take your mail, and the record to fix it.
A few seconds
Or see it done for a domain we watch
Digital Footprint
Lookalikes
Email Authentication
Deliverability
What Gmail's bounces mean
| Code | What it means | What to do |
|---|---|---|
| 421 4.7.26 | Rate limited because the message is unauthenticated. Gmail requires SPF or DKIM of every sender. | Publish SPF, sign with DKIM, or both. |
| 550 5.7.26 | Blocked because the sender is unauthenticated. | Publish SPF, sign with DKIM, or both. |
| 451 4.7.26 | The domain's DMARC policy refuses unauthenticated mail, and a temporary DNS failure stopped the check. | Check that your DNS answers reliably. The sender tries again. |
| 421 4.7.27 | Rate limited because SPF did not pass. | Add the server that sent this to your SPF record. |
| 550 5.7.27 | Blocked because SPF did not pass. | Add the server that sent this to your SPF record. |
| 421 4.7.30 | Rate limited because DKIM did not pass. | Check the key in DNS against the key the service signs with. |
| 550 5.7.30 | Blocked because DKIM did not pass. | Check the key in DNS against the key the service signs with. |
| 421 4.7.32 | Rate limited because the From domain is not aligned with the SPF or DKIM domain. | Sign with DKIM as your domain, or send from a return path under it. |
| 5.7.32 | Blocked because the From domain is not aligned with the SPF or DKIM domain. | Sign with DKIM as your domain, or send from a return path under it. |
| 421 4.7.40 | Rate limited because the sending domain has no DMARC record, or the record has no policy. | Publish a DMARC record. The check above gives one. |
| 550 5.7.40 | Blocked because the sending domain has no DMARC record. | Publish a DMARC record. The check above gives one. |
| 451 4.7.24 | The SPF record of the sending domain has suspicious entries. | Remove entries that allow very wide ranges or that you do not recognize. |
| 451 4.7.23 | The sending address has no reverse DNS (PTR) record. | Ask whoever runs the sending server to publish one. |
| 550 5.7.25 | Blocked because the sending address has no reverse DNS (PTR) record. | Ask whoever runs the sending server to publish one. |
| 421 4.7.29 | Rate limited because the connection did not use TLS. | Turn on TLS at the sending server. |
| 421 4.7.28 | An unusual rate of mail from this sender. | Slow down, and look for a sudden rise in volume or complaints. |
A 4xx code is a delay, and the sender tries again. A 5xx code is a refusal. These are the codes about authentication; Google lists the rest.
What Gmail asks for
Every sender needs SPF or DKIM, forward and reverse DNS for its sending addresses, TLS, and a spam rate below 0.3%. A bulk sender needs SPF and DKIM, a DMARC record at p=none or stricter, a From domain aligned with SPF or DKIM, and one-click unsubscribe on marketing mail. Google's sender guidelines.