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

You can use it to curate listicles. Imagine your marketing department needs to create a list of websites that have run their PR campaign. They can keep that data in Airtable or Google Sheets. The developer then displays on a simple webpage in a card like https://nomadlist.com There are sites like https://sheet2site.com & https://table2site.com that automate this feature. You can also create custom apps with it.... - Source: Hacker News / almost 3 years ago