fair point. i thought about only server side errors (like a one-off timeout connecting to SES).

i don't want to configure too many re-tries, because remember we have a batch invite job that can possibly lead to too much work. how about 5 retries over 4½ hours, retrying every 1, 2, 13, 69, 261 minutes, to begin with ?

obviously, we'll have to tune this to our needs as we go forward.