I am writing a program that will be sending external emails using
postfix with the
mail -s command and I need to verify that the email was sent to the specified address.
In which case, I am curious if
postfix right away reports an error that I am able to get as a return code if email failed sending or if
postfix will say it was a success as long as a valid email (firstname.lastname@example.org) was entered and then later report in a log file or such that the email was unable to be sent?
Also if the network is down, will
postfix still return success as long as a valid email address is used, or will a failure be reported right away?