Hi Chris

This is what our software guy reported a few weeks ago - we also have our domain unable to receive invoice copies but gmail works. A few customers also are not receiving invoices at their domains. He may be confirming what you are saying - but QB appear unable/unwilling to spend the time to fix.. 

It is the Quickbooks server not your email that is the problem.

https://www.spamcop.net/w3m?action=blcheck&ip=167.89.58.138  - this is one of the ip addresses quickbooks use, 167.89.58.229 is another being blocked

Query bl.spamcop.net - 167.89.58.138

167.89.58.138 listed in bl.spamcop.net (127.0.0.2)

If there are no reports of ongoing objectionable email from this system it will be delisted automatically in approximately 6 hours.

Causes of listing

• System has sent mail to SpamCop spam traps in the past week (spam traps are secret, no reports or evidence are provided by SpamCop)
• SpamCop users have reported system as a source of spam less than 10 times in the past week

Express-delisting is not available

Listing History

In the past 79.7 days, it has been listed 15 times for a total of 13.7 days

Other hosts in this "neighborhood" with spam reports

167.89.57.163 167.89.58.229 167.89.59.62 167.89.59.70 167.89.59.73

Dispute Listing

If you are the administrator of this system and you are sure this listing is erroneous, you may request that we review the listing. Because everyone wants to dispute their listing, regardless of merit, we reserve the right to ignore meritless disputes.
Dispute listing of 167.89.58.138