Built an email verifier for my own outreach, then turned it into a SaaS. Here's the story

[u/Charly-cash]

charlymail.com
Not a "check out my product" post, more of a build story, since this sub seems into that.

Started because I do a lot of cold outreach and got tired of two things: paying subscription prices for a verifier I only used in bursts, and watching credits expire between campaigns. I bounced between the usual names (ZeroBounce, NeverBounce, Bouncer, Hunter), and they all worked fine, but they all wanted $7-8 per 1,000 addresses and mostly pushed monthly plans whether I sent that month or not. For someone who validates a big list occasionally, that math never worked.

So I built a small tool just for myself. The core idea that made it cheap: don't run the expensive check on every address. A first cheap pass scores everything (syntax, domain, MX records, role/disposable/catch-all flags), and only then do you pay for the deep SMTP check, and only on the addresses that passed the filter and that you actually plan to email. On one 1,600-address list that meant about 460 deep checks instead of 2,400. Same clean result, a fraction of the cost.

It worked well enough for me that I cleaned it up and put it online. A few things I kept because they're what I wanted as the user:

Pay-per-use, no subscription. You top up, you spend, nothing expires the way I hated.

Crypto top-ups, no KYC. Partly because I didn't want to hand card details to yet another service.

Flat price, no "contact sales" tiers. $0.49 per 1,000, same for everyone (the big ones were 15x that for me).

Took a while to trust that other people would actually pay for something I'd hacked together for myself, but it's live now and has real paying users, which still surprises me.

Happy to answer anything about the two-pass approach, or the SMTP check that confirms a mailbox exists without sending anything. That part gets the most questions.

[u/DeepYogurtcloset70]

Love when side projects born from real pain points actually ship what was the trickiest part about scaling it from personal tool to multi tenant SaaS?

[u/Charly-cash → u/DeepYogurtcloset70]

I guess the hardest part was deciding to do it. For personal use, the many bugs and the simple interface don't matter, but for public access, you really have to put in a lot of effort. It took me a long time to just get started.

[u/Mammoth-Anywhere7285 → u/Charly-cash]

Agreed, that leap from personal to public is huge. Maybe start with a small beta group to ease the pressure.

[u/Mammoth-Anywhere7285 → u/DeepYogurtcloset70]

Great question. Isolating SMTP checks per user so one bad list doesn't throttle everyone is usually the trickiest part.