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What
makes e-mails bounce?
In
computer jargon, a bounced e-mail is one that never arrives in the
recipient's
inbox and is sent back, or bounced back, to the sender with an error
message that
indicates to the sender that the e-mail was never successfully transmitted.
But
what happens when someone sends an e-mail out into cyberspace, and
why
do e-mails sometimes bounce back?
When
a user attempts to send an e-mail, he is telling his e-mail system
to look for
the domain of the recipient (for example, webopedia.com) and the
domain's mail
server. Once the e-mail system makes contact with the recipient's
mail server, the
mail server looks at the message to determine if it will let the
message pass through
the server. If the recipient's server has predetermined that it
is not accepting e-mails
from the sender's address (for example, if it has blocked the address
for anti-spamming
purposes), the server will reject the message and it will subsequently
bounce back
to the sender. The message will also bounce back to the server if
the mail server on
the recipient's end is busy and cannot handle the request at that
time. When an
e-mail is returned to the sender without being accepted by the recipient's
mail
server, this is called a"hard bounce".
Once
the e-mail has been accepted by the recipient's mail server there
are still ways
for the message to be rejected. The mail server has to determine
if the recipient actually
exists within its system and if that recipient is allowed to accept
e-mails. If the recipient's
address does not exist on the mail server, then the message will
be rejected because
there is no one to deliver the message to. If the sender misspells
the recipient's address
then the system will recognize this as a nonexistent address and
bounce the message back.
If the recipient exists but does not have enough disk space to accept
the message
(i.e., if his e-mail application is filled to storage capacity)
then the message will bounce
back to the sender. Some mail systems predetermine a maximum message
size that
it will accept and will automatically bounce the message if it exceeds
that size and
some mail systems predetermine a maximum amount of disk space the
user is allowed
to occupy on the server. When an e-mail is returned to the sender
after it has already
been accepted by the recipient's mail server, this is called a "soft
bounce".
Occasionally,
a network failure at the sender or recipient end will cause an e-mail
to bounce back to the sender. Typically, a bounced e-mail returns
to the sender
with an explanation of why the message bounced.
From
... PCWebopaedia.com
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