This is the first time I test run sending by Gmail (custom domain, not @gmail.com) but got into this error.
I have also tried Reconnect to Gmail from My Apps!
Does anyone have any idea? I did a search on this forum and it seems that this problem is very rare.
![](https://uploads-us-west-2.insided.com/zapier-ca/attachment/dfdfc4c8-c0cc-45a5-b49e-63df848eb30d.png)