I've been using Gandi's free mailboxes since 2019 when I de-Googled, they provide easy setup for SPF/DKIM/DMARC. Not sure about the other two. No significant deliverability issues to report. They offer IMAP and a choice between two web UIs which is all I need.

I'd be more than happy to pay for their service in general, just not under duress. If they'd have given me 6 months to onboard I'd have been perfectly fine with $3/mo for email. If I'm going to be abused with a false sense of urgency and pushed to make a quick decision, I'll just leave.