Why am I unable to create an email account that forwards to an AOL Hotmail,Gmail,Yahoo,Verizon and Comcast's email accounts

Due to the increased in ISPs and Web Hosting companies including ourselves being black listed by major email service providers, eg. AOL Hotmail,Gmail,Yahoo,Verizon and Comcast's email automated SPAM filter from time to time, so all email being automatically forwarding to AOL Hotmail,Gmail,Yahoo,Verizon and Comcast from our mail will be discarded

Take AOL as an example, if we set auto forwarding to AOL email account.
What that means is:
  1. You set up the forwarding address you@yourdomain.com with us
  2. you@yourdomain.com forwards to you@aol.com
  3. Someone sends spam to you@yourdomain.com
  4. That spam is forwarded to AOL
  5. AOL receives the forwarded spam and their server assumes the spam came from myASP.NET (in fact it did not, we are merely relaying it)
  6. AOL blocks our servers
That's a simplified explanation, but close to what actually happens. AOL considers the forwarder to be the spammer and eventually that gets our servers blocked. That is why a growing number of hosts will not allow forwarding accounts to point to any address at AOL, same as to Hotmail,Gmail,Yahoo,Verizon and Comcast

We suggest you to use POP3 retrieval instead of auto forwarding. click here for more information about POP3 retrieval
Please note, you can set up forwarding all message to postmaster account first if POP3 retrieval has account limitation.