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Export & send with your ESP

MailInApp can send on its own — natively from your own domain or through your own SMTP relay — so this workflow is entirely optional. If you already run an ESP with lists, automations and sender reputation built up there, you don't have to leave it: design and compile the email here, then hand delivery to the ESP you already trust.

The workflow

  1. Finish your design in the studio.
  2. Export the compiled HTML. This single file contains all three fallback tiers — kinetic, static, and Outlook markup — plus links to the hosted interaction endpoints and live view.
  3. In your ESP, create a campaign using its custom HTML / paste-in-code option and paste the export.
  4. Send a test, then send the campaign like any other.

Any ESP that accepts custom HTML works, including Mailchimp, Brevo, SendGrid, Klaviyo, Campaign Monitor, ActiveCampaign, HubSpot and Mailjet.

Things your ESP still does

  • Delivery, domain authentication (SPF/DKIM/DMARC), list management, unsubscribes and open/click tracking. Keep your unsubscribe merge tags and footer requirements exactly as your ESP expects.

Things MailInApp does after the send

  • Hosts the interaction endpoints that record poll votes, ratings and form submissions.
  • Hosts the live view and hosted form pages.
  • Aggregates interaction analytics per project.

The Gmail 102KB rule

Gmail clips any message whose HTML exceeds roughly 102KB, replacing the rest with a "View entire message" link — and a clipped message loses its <style> block, which silently disables all kinetic interactivity.

The studio tracks your compiled size against this budget while you design and warns you as you approach it. If you hit the ceiling: shorten copy, remove unused blocks, and let images do the visual heavy lifting (image bytes don't count — only HTML does).

Test before you ship

Rendering bugs love production. Before a real send:

  1. Send a test through your actual ESP (some ESPs rewrite HTML slightly).
  2. Open it in Gmail web and on a phone.
  3. If your audience includes corporate recipients, check classic Outlook — you should see the intentional Outlook tier, not a broken layout.