Nothing to add, except that if you are updating multiple sites on a regular basis, check out https://infinitewp.com/. Source: almost 2 years ago

If you have lots of sites, and you need a single dashboard giving direct access to all of them, take a look at InfiniteWP or ManageWP. Source: over 2 years ago

Https://infinitewp.com/ have used for several years now. Source: almost 3 years ago

If you are managing multiple unrelated sites check out InfiniteWP. The free base set of tools will let you handle all updates across them quite easily. Source: over 3 years ago

I bought a lifetime license to InfiniteWP maybe 6-7 years ago. https://infinitewp.com/. Source: over 3 years ago

You should check to see if the messages that are being sent contain any links that would be considered questionable/spammy. You can also try taking the content of one of the messages and checking it’s spam assassin score ( https://spamcheck.postmarkapp.com ). Source: over 2 years ago

Build a clean email that passes a spam check with flying colors (https://spamcheck.postmarkapp.com/) then use a warmup service like lemwarm, inboxally or neverspam as mentioned in the other comments. Source: almost 3 years ago

The issue sounds more email centric. You're likely hitting the Apache SpamAssassin limit on the remote email servers. Use https://spamcheck.postmarkapp.com/ to check the score of emails you've had declared spam, and follow recommendations to improve. Source: about 3 years ago