RL000001: rate limited by sender reputation

What it means

Xfinity applies rate limits to all inbound mail. When a sending server goes over its limit, Xfinity answers with a 4xx temporary failure, which tells the server to try again later, so the mail is delayed while the server keeps retrying. For RL000001 the limit depends on sender reputation as measured by SenderScore and on authentication of the sending server, whatever the number of domains it sends for. Xfinity publishes the scale: 1,200 recipients an hour at a SenderScore of 0 to 15, rising in steps to 60,000 an hour at 86 to 100, and 120 an hour where no score applies, all subject to successful authentication.

Common causes

• Your server sent to more Xfinity recipients in an hour than your SenderScore allows.
• Your SenderScore is low or missing, which leaves a small hourly allowance.
• Authentication of the sending server failed, and Xfinity's higher limits depend on it.

How to fix it

1. 01Let your server keep retrying. Xfinity's own advice is to shorten the delivery retry interval if the limit is hurting delivery.
2. 02Spread sends to Xfinity addresses over more hours so you stay under your hourly allowance.
3. 03Check your IP's SenderScore, since a higher score raises the hourly allowance.
4. 04Make sure SPF and DKIM pass for your mail, since the published limits assume successful authentication.
5. 05If you need more help, use Report an issue under Postmaster on Xfinity's Customer Security Assurance site.

Sources

What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.

• Troubleshoot Comcast.net email error codes (Xfinity)xfinity.com

Further reading

• Why sender reputation drops