Mail splitting in relaying MTAs
If a sender in Europe
sends a message to two or more recipients
in North America, only one copy might be copied across the
expensive Atlantic cables as shown in the figure below:
handle mail, unless either the recipient or the sender is local to
the MTA. Thus, the saving shown above requires an agreement with the
MTA which splits the message after transport across the Atlantic.
This was not always so. In the beginning of the 1990-s, most MTAs
were willing to forward mail for any recipient. The reason why this
was abolished in the middle of the 1990-s was that spammers used this
feature to get foreign MTAs to help them split mail to millions of
recipients. Some so-called experts claimed that spamming could be
stopped by forbidding splitting of mail by other than the MTA of the
sender or the recipient. They enforced their view by implementing a
program which scanned all MTAs everywhere, checking that they did not
allow foreign splitting, and sending angry letters to non-conforming
MTA administrators (postmasters) threatening to stop receiving mail
from them unless they stopped splitting. This is an interesting
example of how the Internet is regulated in dubious ways by
pseudo-police-authorities. Spamming could be counteracted more
efficiently using other methods than this.
Here I am flaming: giving my personal opinion on a controversial issue. Other experts have different opinion on this.