Golang x/build/cmd/relui: error sending release annoucement email

SendGrid returned:

unexpected status 401 Unauthorized, want 202 Accepted; body = {"errors":[{"message":"Maximum credits exceeded","field":null,"help":null}]}

Example: https://build.golang.org/releases/workflows/c4971d72-1ad1-444d-aaf1-bab3144d29d7

Comment From: mrkfrmn

CC'ing @golang/release.

Comment From: mrkfrmn

Just pasting over some details from discussion elsewhere.

@dmitshur pointed out that we use SendGrid to send release emails, which was on a free tier until July 26th; the tier itself was retired. It's not entirely clear what the best approach is for programmatically sending email, but we need to do something. Seems we can manually email in the meantime.

See issue #47405.

Comment From: gopherbot

Change https://go.dev/cl/691976 mentions this issue: cmd/relui: add a Mailjet-based SendMail implementation

Comment From: gopherbot

Change https://go.dev/cl/691975 mentions this issue: cmd/relui: let the release coordinator handle sending mail, if needed