Good morning.
Starting early January 2017, users in my domain (nevosi.com) have been having extensive trouble both emailing to and receiving email from Symantec Email Security.cloud customers -- primarily cbts.net and cinbell.com domains. This does not affect all emails, but rather only certain emails such as emails with attachments, replies to emails received from cbts.net/cinbell.com users, and meeting requests. Failures are met with an 553 rejection (after the message content has been transmitted) similar to the following:
Remote Server returned '<cluster6.us.messagelabs.com #5.0.0 smtp; 553-Message filtered. Refer to the Troubleshooting page at 553-http://www.symanteccloud.com/troubleshooting for more 553 information. (#5.7.1)>'
This issue started after an issue with the provider who hosts our reverse DNS resulted in no reverse resolution for our network. This reverse DNS issue was rectified a few days, however we continue to have issues sending to/receiving from Symantec Email Security.cloud customers.
Our MTA is nv-dc2-mail1.nevosi.com/198.187.23.231
As I stated above, reverse DNS is back in place for this MTAs:
nv-dc2-mail1.nevosi.com. 523 IN A 198.187.23.231
231.23.187.198.in-addr.arpa is an alias for 231.192-26.23.187.198.in-addr.arpa.
231.192-26.23.187.198.in-addr.arpa domain name pointer nv-dc2-mail1.nevosi.com.
This MTA's IP addresses is covered by an SPF record that covers nevosi.com which has been in place since 2010:
nevosi.com. 599 IN TXT "v=spf1 mx ip4:198.187.23.192/26 ip4:10.245.0.0/24 ~all"
I have verified that SPF and DKIM both validate by emailing a Gmail account and clicking "Show Original" for the message which reports the following:
SPF: PASS with IP 198.187.23.231
DKIM: PASS with domain nevosi.com
The Symantec Email Security.cloud IP Reputation Investigation tool (http://ipremoval.sms.symantec.com/lookup/) reports the following:
"The IP address you submitted, 198.187.23.231, does not have a negative reputation and therefore cannot be submitted for investigation.", and
I even resorted to spinning up another MTA and attempting to relay messages through it, but those messages are rejected as well, so I have reverted that change and am back to using nv-dc2-mail1.nevosi.com/198.187.23.231.
Can anyone with Symantec please assist? I have exhausted all possible avenues as a non-customer; I simply want to be able to send emails to and receive emails from your customers. I would be most appreciative of any assistance.
Thank you in advance,
-jd