Gmail will soon stop support for the 3DES encryption cipher for incoming SMTP connections

What’s changing

Starting May 30, 2025, we will no longer support the Triple Data Encryption Standard (3DES) for incoming SMTP connections. After May 30, 2025, email systems using 3DES for SMTP connections will be unable to deliver emails to Gmail accounts. This change is necessary to improve our security and protect you from potential vulnerabilities associated with outdated encryption methods.

To prepare for this change, please ensure that all of your sending systems are configured to use more modern and secure TLS ciphers. A list of supported ciphers can be found in our Help Center.

Getting started

• Admins: 
• Visit our Help Center to learn more about Ciphers for Gmail SMTP TLS connections.
• If your domain has recently sent messages to Gmail using 3DES, you have also received notification via email with additional information.
• If your end users are receiving these types of messages, they will see a warning informing them that this specific cipher will no longer be supported. Visit the Help Center to learn more about checking your email traffic sent over 3DES connections.

Availability

• This change impacts all Google Workspace customers

Resources