- - - O O O P S - - -
Is your IP "10.5.1.22" being blocked?
If so, it may be on a block list.
You can find out, here are some popular and simple online sites that allow you to search multiple block lists simultaneously for your IP status:
1. http://MultiRBL.Valli.org 2. http://E-DNS.org 3. http://JustSpam.org 4. http://UnifiedeMail.net
You can also lookup your IP/networks' SBRS (Sender Base Reputation Score) at http://SenderBase.org (Cisco IronPort SenderBase Security Network)
You should always review your IP RDNS record via external public DNS server only to confirm proper RDNS status; if none are accessible, you may use this free and simple online NSLOOKUP tool: CentralOps.net/co/NsLookup.aspx