IPv6 connectivity to mx[1-4].smtp.goog.

Tue Feb 27 13:02:46 UTC 2024

Hi,

At https://internet.nl we're seeing IPv6 connection issues on TCP port 
25 (SMTP) to mx[1-4].smtp.goog.

Either 100% DROP (so no TCP connection) or ⅔ failure to setup connection.

Further testing seems to confirm the problem is bigger and on Google's side.

So, this fails:

echo 'quit' | nc -6 -w 3 mx1.smtp.goog. 25

and this works:

echo 'quit' | nc -4 -w 3 mx1.smtp.goog. 25

(on MacOS use -G instead of -w)

Is anyone else seeing this? Any idea what is causing this?

-- 
Marco