As of June 5,2023, SendGrid will no longer accept connections for sending mail via SMTP or API without TLS v1.2 or higher.
Communication surrounding this change was sent beginning in February with additional communication sent between February and June 5, 2023. Please note that we are unable to provide extensions for this requirement.
With deprecation of support for TLS 1.0/1.1, you will need to ensure that all servers that connect to SendGrid in order to send mail utilize TLS 1.2 or higher. This generally involves updating your libraries to a version that supports at least TLS 1.2.
Our external documentation on this change can be found here. The documentation includes options for testing on multiple languages and using both our API and SMTP platforms.
It is important to note that Twilio SendGrid Support's insight into your systems are limited. Ensuring that all servers that connect to SendGrid are using TLS1.2 or higher, should resolve these issues. Some error messages you may see that could indicate an issue with your TLS version could be:
Authentication failed because the remote party has closed the transport stream
An existing connection was forcibly closed by the remote host
The underlying connection was closed: An unexpected error occurred on a send.
SSLHandshakeException: Remote host terminated the handshake
If SMTP issues began on June 5th, 2023, it is likely that your servers have not been updated to utilize TLS 1.2 or higher. Please check the servers used to connect to SendGrid to ensure that those servers are utilizing TLS 1.2 or higher.