I am administering a server that hosts a mail server(sendmail, dovecot,spamassassin,clamav) and webserver (httpd, squid). The last a couple of days I have problem with e-mail, when another mail server requests (for example a bank ) reverse lookup in order to accept my e-mails. It seems like there is no in-address-arpa for my domain. The current setup,doesn't actually need a full blown DNS Server because my ISP provides DNS resolution for me.
When I contacted my ISP to add a PTR record their reply was that the problem is with the ISP of the remote site(bank) and not with them.
But I have e-mails that are for other recipients and they also stay queued because of the same problem.In the past I never had a problem and I haven't changed anything from my setup
By the way I have upgrated my Centos to CentOS 5.2.
Any clues?
I still think the problem is with my ISP.
Any suggestions on whta can I look for?

The PTR records need to be added by the person who is responsable for the DNS from your domain,
In your case the ISP

Thanks a lot that was my thought as well.
No another question can I build software raid on top of LVM.What I mean is that can I use a disk that is configured all ready with lvms.
My Disks are
/dev/sda 73GB
/dev/sdb 73GB
/dev/sdc 450GB DATA WILL BE STORED HERE
/dev/sdd 450GB DATA WILL BE MIRRORED HERE

My server is DELL PowerEdge 2970

If during installation I configure my /dev/sda disk with three partitions /dev/sda1 /boot , /dev/sda2 /swap , /dev/sda3 / , and ofcourse my root is on vg00 and it has seperate partitions for /root, /home, /var, /usr. Will be able post install to create three raid devices with mdadm
/dev/md0 raid1 with membership of /dev/sda1 and /dev/sdb1 (boot )
/dev/md1 raid1 with membership of /dev/sda2 and /dev/sdb2 (swap on both)
/dev/md2 raid1 with membership of /dev/sdc1 and /dev/sdd1 (root )