Quote:> Another problem : I want to contact someone by email but
>his email address consists of symbol '%' or '!' that when I send
>mail to him then the mail return to me because unknown user host.
>Mail address is wrong , or I send it wrong method.
These are both holdovers from before the time of MX records. They are
all obsolete now, but some people still use them.
Summary: The '!' is for a UUCP-style bang-path.
Details: Let's say you're on a UUCP network. Your machine is fred,
and you're connected to a machine named wilma, which is connected to a
machine named betty. You want to send mail to user barney on system
betty. The address you have to use is "wilma!betty!barney", meaning
"send this mail to wilma, who will forward it to betty, who will
deliver it to barney".
Summary: The '%' is a similar convention for internet style mail to
machines that are not on the internet.
Details: Let's say some company, HAL Computers, has their own private
TCP/IP network, with full mail and everything, which is not on the
internet. Now let's say they get one machine, "hal.com", and put that
on the internet. A user on their internal network may be addressed as
However, "hal.com" knows how to deliver mail to "bar.hal.com". So,
you send mail to hal.com, but tell it to deliver its mail to
so you replace one of them with a '%' sign. So, the address you use
to do the delivery all over again.
With MX records, you slip a record into the nameserver that says "when
you want to send mail to bar.hal.com, you should deliver the mail to
hal.com, who will figure out where the mail really goes". With the
advent of widespread MXing, ! and % have virutally disappeared from