Wanting to make sure I've done everything I can to prevent our legitimate email from being incorrectly marked as spam by other companies:
Exchange 2010 with SP1, no major changes in 6 months.
I've run email for this particular 30-user business for nearly a decade, but the last few months their emails are starting to be caught by their customers/partners spam tools. These are human to human emails outgoing from my Exchange servers to other companies. When one or two starting saying company X or Y isn't receiving my emails I think it's a fluke, but now it seems to be up to 5 people internally having issues with 1/2 a dozen of their customers/partners on every email, sometimes just new emails, sometimes replies.
- I have a proper PTR record matching hostname
- My email domain matches MX domain name and the EHLO response
- On no blacklists according to mxtoolbox.com
- senderscore.org is all good and shows score of 100
- SPF/Sender ID setup correctly
- Exchange 2010 doesn't support DomainKeys so I'm not doing that
- No spam or marketing emails are sent from this server/IP
- All sending email is human generated
- IP is from a colo not residential ISP
- no complaints of email not getting to email providers (hotmail, gmail, yahoo, etc.)
Any further ideas? At this point all I have to say to people is "totally out of our control", unless I want to work with each company to find out their anti spam vendor and contact each one for resolution...
Thanks for any ideas!