Alan J. Flavell wrote:
>
> Occasionally, an attempt to verify a sender address (e.g at yahoo.com)
> via callout produces a response:
>
> 421 VS14-RT5 Mailbox bounce arrival rate exceeds system limit (#4.2.2)
the number of bounces arriving in a fixed time interval to that mailbox
trips a limit that yahoo has in place.
two probablities - spamrun, or a virus forging the yahoo mailbox in its
envelope
srs