As the issue seems to be caused by intuit servers being blocked because of the volume of spam emails being sent through them I doubt they can find an easy solution.

It shouldn't really be that hard for intuit to get it fixed as there are plenty of organisations that get their email addresses spoofed but don't end up on blacklists for months.

It looks like intuit play for time waiting for their IP addresses to be released from the blacklists.

My company develops software and one thing I can assure you is it shouldn't take months for a fix to a simple issue such as this, either there is a fix and its developed tested and deployed in a week or so or there isn't a fix, looks to me like the latter, we shall see.

I would have thought that the best solution if intuit cant fix it would be to use customers own domain to send emails. This would require users to set up their email domain via the intuit settings and wouldn't be that hard to incorporate. Whether you would want to trust intuit not to be hacked and your email passwords be compromised is a different matter.

For users that do not have their own domain for email intuit could offer the service for add on email via a third party plugin.