Update: the plugins only confirmed that e-mails weren’t being sent from my WordPress site. Couldn’t get it done with whatever setting I tried.
It’s a website I’m setting up for work, so I got back to it today. Got it fixed!! This saved me (in case anyone else has got this problem and uses Outlook/Office 365):
https://www.poremsky.com/wordpress/send-email-generated-self-hosted-wordpress-website-using-office-365/
I used the plugin ‘Configure SMTP’ to fix my e-mail settings.
Your plugin works beautifully now. Thanks for you help!