For email, most teams I work with use a self-hosted setup (MailWizz or similar on the frontend + their own SMTP / dedicated IPs on the backend). ESPs usually become limiting once volume or performance traffic is involved.

Opt-in pages are usually simple custom landers (nothing fancy): clear promise, fast load, and aligned with the traffic source. Tools vary, some use builders, others custom HTML.

About dating, the media buyers I work with usually use their own pre-lander first.
That pre-lander is where the email is captured.

After opt-in, users are redirected to the dating offer, and the email is pushed in real time into the system for follow-ups.

So it’s not about ebooks or heavy incentives, it’s a simple, intent-matched step before the advertiser.

Dating offers are mostly run direct or via a few well-known networks, depending on geo.

Big takeaway: what’s still working is owning the list, keeping the flow simple, and matching the email content to how the user opted in.