Google will No Longer Support THIS Encryption in Gmail - Here's What's Changed

Google announced it will discontinue support for the 3DES encryption cipher in Gmail’s inbound SMTP traffic, effective October 31, 2025. The change comes as part of ongoing efforts to improve security standards across Google Workspace.

3DES, or Triple Data Encryption Standard, is an older cryptographic protocol that has long been considered weak by modern standards. Gmail currently supports 3DES for compatibility only with legacy systems. Google cited the cipher’s known vulnerabilities as the main reason for its removal.

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Gmail will no longer accept inbound messages from mail servers that attempt to use only 3DES for encryption. Instead, email providers are expected to use stronger ciphers that meet current security benchmarks. TLS 1.2 or higher is recommended, and Google has pointed to industry-standard tools like Hardenize and Qualys SSL Labs to assist with compliance testing.

Google says it will begin rejecting messages encrypted with only 3DES starting in October 2025. Mail services still dependent on the cipher are advised to upgrade their configurations well before the deadline to avoid delivery issues.