I didn’t know that the guy behind WPForms is the same of OptinMonster, Envira Gallery and Monster Insight… I’ve checked the bio of Syed Balkhi (https://syedbalkhi.com/about/) and it’s quite impressive – especially its age, 25. Congratulations to him!

More on topic: SMTP is a must for a modern website, but to avoid the antispam filters you also need DNS control in order to setup SPF, DKIM and DMARC records. Alas, no WordPress plugin can do that for you…