Ok, for few months that I have been using Gmail, I never got any mail delayed messages nor any Mail failure messages. This morning all of a sudden I got a mail delayed message for a message that I send for more than 24 hours ago. I tried sending email to not valid email address and I got Mail Delivery failure message straight away. I have tried the same experiements before too, but did not get any mail failure messages than.
This messages and step definately helps me to trust Gmail more than I did 10 minutes ago.
Tejas Patel