RedHat Linux 8.0 setup for a mail server with sendmail. Nothing was modified and all of a sudden I cannot connect to the internet, I believe that is why email cannot be sent/received anymore as well (the BIG problem). HELP PLEASE!!
I can ping the firewall and router, cannot ping anything outside our LAN, outside cannot ping the mailserver by name or IP. I talked to our DNS folks and they say everything checks out on their side.
# Do not remove the following line, or various
# that require network functionality will fail.
220.127.116.11 mail mail.csha.us
host = local, bind
nslookup for our domain.......
csha.us mail exchanger = 50 mail.csha.us.
nslookup for another domain.....
*** Can't find yahoo.com: No answer
Trying to send an email out gets the error, "550 5.1.2 <email@example.com>... Host unknown (Name server: yahoo.com: no data known)"
Trying to send an email in from outside gets the error, "Connected to 18.104.22.168 but sender was rejected. Remote host said: 553 5.1.8 <firstname.lastname@example.org>... Domain of sender address email@example.com
does not exist"