Having worked in IT for decades sending millions of emails into an the major inbox providers I can say that unless your brand is being targeted by a coordinated campaign, spending the time to set up processing of both the transaction and forensic emails isn't worth the effort. If you are a smaller shop, consider not spending a great deal of time on it until you actually need it.
Edit to say if sending to Gmail recipients take the time to set up the free Postmaster tools provided by Google to give you the ability to keep an eye on both IP and domain reputation and use "good" content email streams on your lower reputation IPs to bring them back into acceptable ranges while moving transactional emails around to avoid watering down remarks email streams with high-engagement content.
are there any Free Software tax programs that are kept up to date with tax codes? I would so prefer not to have a for-profit company handling my taxes.
It's a piece of software I've developed that is not publicly released, but eventually will be and will be AGPL3.
A few other people have also written such software. One guy still maintains it and surprisingly wrote a whole IRS / 1040 library in C. Mine is more oriented towards business and employer related taxes, though, than personal / investment sort of tax forms (although it will do the latter).
Biggest weakness is it will only support 1 or 2 states because I don't have the resources to make an accurate system for all 50.
There has been a lot of progress towards mapping all near-earth asteroids, at least. That's a lot better than the previous tactic of putting one's fingers in one's ears and humming.
Edit to say if sending to Gmail recipients take the time to set up the free Postmaster tools provided by Google to give you the ability to keep an eye on both IP and domain reputation and use "good" content email streams on your lower reputation IPs to bring them back into acceptable ranges while moving transactional emails around to avoid watering down remarks email streams with high-engagement content.