Exchange 2010 send/recieve troubles with just a few domains, others working fine
Posted on 2014-04-11
About five weeks ago we started getting email rejection notices for only certain domains we send to. We also started getting phone calls that we could not receive email sent to us from just a few domains. 90% of the in/out email is working without trouble but a few select domains started having trouble either sending or receiving with our domain. No update or changes that I can think of on environment.
When our email is rejected, we receive a delay notice or two and finally a rejection with '#550 4.4.7'
The rejection notice going back those who we can not receive from is '451 Timeout Trying to Verify RCPT'
VMware VM Server 2008 R2 with Exchange 2010 running Forefront, domain name is domain.com and using iPage hosting and mail traffic via mail.domain.com
Troubleshooting so far:
- Scanned entire network with AV and Malwarebytes...everything shows clean at servers and workstations
- Checked blacklists, nothing listed for our domain or the domains we have trouble with
- MXToolbox shows no Reverse DNS PTR record found and time out delay warning but not a failure
- Messages in Exchange queue are all valid from good senders to good addresses with code 451 4.4.0
- Put in a work ticket with ISP for a PTR record to be established, not complete yet
- No SPF record in DNS, I need help creating and installing one if anyone thinks it would help, I'm a noob with this
- Our domain has been using the server's own self authored security certificate for years without trouble but I'm thinking of purchasing an authority authored one and installing it if you guys think it would help?
- I've added domains to whitelist in ForeFront and via the exchange powershell for domains that we could not receive email from, no help