API-First Infrastructure: How Lidgen Scaled Its Mailbox Stack on InboxKit

Boaz Zaidler was running Lidgen's infrastructure on ZapMail and wanted a platform built around API access, since Lidgen manages everything programmatically rather than by hand.

At the time, I was using ZapMail and I was looking for a better solution that is API-driven, because we like to manage the infrastructure with API. I looked for the best pricing, and this is how I got to InboxKit.

— Boaz Zaidler, Founder of Lidgen

For a platform onboarding clients constantly, API access to infrastructure isn't a nice-to-have, it's how Lidgen pre-warms domains and adjusts sender details before a client ever sees a campaign.

It's especially important to onboard clients easily. What we like to do is pre-warm domains before the client even onboards, which requires adjustments, like updating the forwarding domain, a URL, or changing names. InboxKit lets us change the sender name through the API, so this is really helpful.

— Boaz Zaidler, Founder of Lidgen

Two features stood out beyond the API basics: tagging mailboxes for easy filtering across clients, and controlling sender profile pictures programmatically, something Boaz says most providers don't even offer.

I really like the tags, even if I go manually, I can filter easily between clients. And I also like the profile picture, this isn't something everybody looks into, but we like to control the profile picture too, through the API, as we change it for the presenters.

— Boaz Zaidler, Founder of Lidgen

Lidgen tests this rigorously, and the results aren't as simple as "add a photo."

We always test, and the data shows it's better to have a picture, but it really depends on what picture and what audience. Some people want to use a young female headshot, but that doesn't necessarily work on C-levels in enterprise, they see through it. A small trick I can share: putting a GIF with animation on there really catches the eye.

— Boaz Zaidler, Founder of Lidgen

Boaz has used ZapMail and other vendors directly. His read: infrastructure alone rarely decides outcomes, but among the infrastructure providers, InboxKit matches the best on performance while beating them on pricing and control.

I think you're at the top. At some point it's not about the infrastructure, it's about the copy, but some providers just don't perform. ZapMail performs too, but InboxKit performs at the same level for better pricing, with better management, at least for me. This is why I'm sticking with InboxKit, we get the best results and the best control.

— Boaz Zaidler, Founder of Lidgen

Moving off both ZapMail and Hypertype landed the clearest savings on Azure mailboxes specifically, but for a platform scaling across many customers, the bigger win was the depth of API control itself.

A hundred percent, cost savings, we have better prices. We didn't only move from ZapMail, but also from Hypertype. Right now we have better pricing on our Azure mailboxes, which is big, I'd say Azure is the big save for us. But for me, the most important thing, because we're scaling and have many customers, is the ability to control everything with the API and manage it in a sophisticated way.

— Boaz Zaidler, Founder of Lidgen

• API access replaces manual mailbox management. Pre-warming, sender name changes, and profile picture control all run programmatically, which is what lets a platform like Lidgen onboard clients fast.
• Tags make multi-client management tractable. Filtering mailboxes by client, manually or otherwise, is a small feature that matters a lot at scale.
• Azure pricing was the direct cost win. Consolidating off ZapMail and Hypertype produced its clearest savings on Azure mailbox pricing specifically.
• Control matters as much as performance. Boaz rates InboxKit's raw deliverability as on par with the best alternatives, the differentiator is pricing plus how much you can manage through the API.

Lidgen is a platform-led B2B outreach service founded by Boaz Zaidler. It pairs a cold outreach platform with experienced campaign managers who review campaigns before they send, positioning itself as a third option between traditional lead gen agencies and fully automated AI SDRs, with personalized outreach at scale and full control over brand reputation.

For more on how Lidgen's model compares with agencies and AI SDR tools, see our breakdown of AI SDRs vs lead gen agencies.

Running outbound for clients?

InboxKit provides the mailboxes, domains, automated DNS, warmup, and full API control that let platforms and agencies onboard clients fast and manage infrastructure at scale. See plans and pricing or explore our agency email solution.