This is not something you install or configure on Exchange.
"Reverse lookup" refers to the DNS.
Normally you have a DNS-record for your mail server,
so that when someone tries to send emails to you, they
check DNS for (for instance) mail.company.com, and get
and IP-adress back.
This mechanism can also be reversed, so that when you
try to send emails to others, the remote mail server will
do a "reverse DNS lookup" on your IP-address, to see if
it comes back with the same domain name as you claim
This is used to counter IP-address spoofing.
Ask your ISP, or whoever manages DNS for you, to insert a reverse DNS
record (a PTR record) for your mail server.
You can check whether a record already exists by doing "nslookup
(substitute your mail servers IP for all the X-es). If you get the mail
hostname back as a reply, then the record is in place.
> not sure how would i check to see if this lookup is
> installed or configured
> >-----Original Message-----
> >Do you have reverse lookups setup for your mail
> exchangers? I had a similar
> >issue, as soon as the reverse lookup was configured all
> was well.
> >> I have had some issues with my exchange server and the
> >> rely option being on. I have since fixed that but I am
> >> having issues sending e-mails to some companys and even
> >> this message below. This does not happen to all e-mails
> >> leaving my company just a about half a dozen or so. its
> >> not ramdem it is all the time.
> >> I was wonding if exchange has an option somewere that
> >> might be blocking these from our side or have we been
> >> on a anti spam list and blocked on there side?? If so
> >> can be done about it can i be removed with out calling
> >> these companys???
> >> Thank you in advanced for help provided
> >> Matthew
> >> Your message did not reach some or all of the intended
> >> recipients.
> >> Subject: testing our e-mail service
> >> Sent: 4/18/02 9:39 AM
> >> The following recipient(s) could not be reached:
> >> "any e-mail address"on 4/18/02 9:39 AM
> >> The recipient was unavailable to take
> >> of the message
> >> The MTS-ID of the original message is:
> >> c=US;a= ;p=ourdomain;l=exchange server-020418133910Z-