Hi. I am subscribed to few mailing list on SF. Recently
I was not able to send a message to any of them.
I am getting this error:
TEMP_FAILURE: SMTP Error (state 9): 451-Could not
complete sender verify callout
451-Could not complete sender verify callout for
451-The mail server(s) for the domain may be
temporarily unreachable, or
451-they may be permanently unreachable from this
server. In the latter case,
451-you need to change the address or create an MX
record for its domain
451-if it is supposed to be generally accessible from
451 Talk to your mail administrator for details.
I am not sure where is the problem and how I fix it.
Thanks for help.