Mail errors · Gmail

What does “421 4.7.29 Your email has been rate limited because you're not using a TLS connection” mean?

The server that sent the message did not encrypt the connection to Gmail.

Last read from the sources at the foot of this page.

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Gmail bounce
Mail Delivery Subsystem
421 4.7.29

Your email has been rate limited because you're not using a TLS connection

As Gmail prints it.
01

What does it mean?

TLS encrypts the connection between two mail servers. Gmail requires it from senders.

02

What exactly does the source say?

421 4.7.29 Your email has been rate limited because you're not using a TLS connection. Gmail requires all bulk email senders to use TLS/SSL for SMTP connections. To set up TLS for email, visit TLS & SSL connections. To learn more about Gmail requirements for bulk email senders, visit Email sender guidelines.

Gmail's page writes domain-name and ip-address where your bounce shows your own domain and the sending address.

Same fix: 550 5.7.29
550 5.7.29 This message was blocked because it wasn't sent over a TLS connection. Gmail requires all bulk email senders to use TLS/SSL for SMTP connections. To set up TLS for email, visit TLS & SSL connections. To learn more about Gmail requirements for bulk email senders, visit Email sender guidelines.
03

Why would a small firm see it?

An older device, a website plugin or a server set up years ago sending mail straight to Gmail without TLS.

04

How do I fix it?

  1. Find which server or device sent the message.
  2. Set it to send through your mail provider with a username and password and TLS turned on.
  3. Send a test message and check that it arrives.
05

What else do the sources say?

Use a TLS connection for transmitting email.

Sources

Where does this come from?

Related
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