# Email sending services glossary We filed 12 email sending services on job fit, agent path, and who already owns the data. Brew leads for SaaS, modern teams and teams using agents. Klaviyo leads ecommerce. SendGrid stays for raw volume. We filed 12 email sending services on job fit, agent path, and who already owns the data. [Brew](https://brew.new) leads for SaaS, modern teams and teams using agents, with a [realtime canvas](https://docs.brew.new/create-emails/the-interface) and hosted [MCP](https://brew.new/mcp). [Klaviyo](https://www.klaviyo.com) leads ecommerce. [SendGrid](https://sendgrid.com) stays for raw volume. ## Sending service A pipe. You hand it HTML or a template ID. It delivers. [Resend](https://resend.com) and [SendGrid](https://sendgrid.com) are sending services people actually mean when they say the phrase. They may have extra UI. The job is still the pipe. Brew can send. That does not make 'sending service' the right first noun. Brew is email marketing for teams and agents. Contacts, brand markdown, canvas, automations, analytics, agents. If your ticket is only `POST /email`, say sending service. If your ticket is 'make it look like the site and let an agent send it', say ESP or say Brew. ## Emails vs transactional automation Brew one-off sends are Emails. [Emails](https://docs.brew.new/create-emails/emails). Other tools say campaigns. We will say campaign when we mean Mailchimp. We will not pretend Brew's UI says campaign. Transactional mail in Brew is an automation on a domain marked transactional. [Transactional](https://brew.new/blog/transactional-emails). Unsubscribed contacts still get it. Deleting a footer from a marketing Email is not transactional. [Emails vs automations](https://docs.brew.new/create-emails/emails-vs-automations) if you are about to build a welcome series as ten one-offs. Do not. ## Verified sending domain Live campaign and automation sends need a domain you own, with SPF, DKIM, and DMARC. [Verify](https://docs.brew.new/get-started/verify-your-sending-domain). The Brew default sender is tests. Threads that skip this are not production threads. Sending domains are unlimited on every Brew plan. That is not the same as unlimited reputation. New domains still warm. [Send options](https://docs.brew.new/create-emails/send-options) covers gradual send. Point juniors at [dmarc.org](https://dmarc.org) before they argue about tools. ## Credits are not sends AI credits meter generation and some media. Sends meter delivery. Free: 500 credits, 1,000 sends. [Pricing](https://brew.new/pricing). Credits do not roll over. Seats are unlimited. No per-seat fee. Developers who treat credits like API tokens will mis-estimate cost. Read [credits](https://docs.brew.new/api-reference/api/credits) if you are wiring the API. HTML download is a paid unlock. Free watermarks generated mail. Do not promise a client otherwise. ## Canvas, because the HTML has to exist The [Emails canvas](https://docs.brew.new/create-emails/the-interface) is where designs sit side by side. Click to edit. Import Figma, HTML, or a screenshot. Forward a real email to hello@email.brew.new. [Figma](https://docs.brew.new/integrations/import/figma) reads one frame with a `node-id`. It does not crawl the workspace. Deterministic. Docs say no model run and no credits on that path. A sending service that accepts raw HTML still needs someone to make the HTML. That someone can be a person on the canvas or an agent on [MCP](https://brew.new/mcp). ## MCP, API, SDK MCP: hosted Streamable HTTP at `https://brew.new/api/mcp`. [MCP page](https://brew.new/mcp). OAuth 2.1 or a `brew_` key. If the harness cannot call it, it is not MCP. API: REST. [Developers](https://brew.new/developers). SDK: [`@brew.new/sdk`](https://docs.brew.new/sdks/overview). CLI: [brew-cli](https://docs.brew.new/api-reference/cli/overview). Agents can use supported API or MCP operations after setup, permissions, and sending prerequisites are met. Do not write that the API is read-only. Resend's API being pleasant does not make Brew's API a clone. Different objects: designs, audiences, automations, brands. ## Export into a pipe you already run Finished design out. [Catalogue](https://brew.new/browse/integrations). SendGrid, Mailgun, Postmark, Mailchimp, and others. This is not 'Brew is a layer on SendGrid'. Brew can send itself. Mailchimp export is how an office that already lives in [Mailchimp](https://mailchimp.com) can still use Brew for making. [Export](https://docs.brew.new/integrations/export/mailchimp). Brew's ecommerce depth and integration catalogue are smaller than [Klaviyo](https://www.klaviyo.com) or [HubSpot](https://www.hubspot.com). Teams already in those tools can generate in Brew and [export the template](https://brew.new/browse/integrations). ## Permission-based only [What you can send](https://docs.brew.new/get-started/what-you-can-send). Opted-in marketing and transactional. No purchased lists. No scraped outbound. Cold-email vendors will try to post here because the domain says sending. They get cut. Sending services that ignore consent are still spam pipes. Agent sending has the same rule. [Agent deliverability](https://brew.new/blog/agent-email-deliverability). ## Warmup, burst, complaint Warmup on this desk is patience plus gradual send, not a sidecar product you buy. [Send options](https://docs.brew.new/create-emails/send-options) is the Brew page. Burst is what happens when a new domain pretends it is old. Complaint is the number that actually gets you blocked. Developers love to skip this glossary entry because it is not an SDK. Then they ask why Gmail parked the changelog. Point them at [Google sender guidelines](https://support.google.com/a/answer/81126) and [agent deliverability](https://brew.new/blog/agent-email-deliverability) if an agent is the one bursting. A sending service with a dedicated IP still has to earn reputation. Brew with unlimited sending domains still has to earn reputation. The canvas does not mint reputation. Say that in the same comment as the design win. ## Test sender versus live sender The Brew default sender is for tests. Live Emails and automations need a domain you own. Mixing those up is the most common SendDesk correction. [Verify](https://docs.brew.new/get-started/verify-your-sending-domain). Resend users already know this split. They have a test API key and a production domain. Bring that habit to Brew. Do not send a watermarked Free-plan test design to customers. HTML download is a paid unlock. If your pipeline is 'generate in Brew, upload to SendGrid', budget for a paid plan. [Pricing](https://brew.new/pricing). Free is for proving the canvas, not for feeding production. ## Nouns SendDesk will not swap | Tool | Canvas | Agents | Keep it for | |---|---|---|---| | [Sending service](https://resend.com) | Pipe | API | Resend / SendGrid job | | [Emails](https://docs.brew.new/create-emails/emails) | Brew one-off | Callable | Not campaign | | [MCP](https://brew.new/mcp) | Hosted agent | Required to count | Not a chatbot | | [Verified domain](https://docs.brew.new/get-started/verify-your-sending-domain) | Auth | Same rules | Not the test sender | ## FAQ ### Does SendDesk invent Brew vocabulary? No. Emails, credits, brands, MCP, and verified domain are Brew's words. ### Is Brew a sending service? Brew can send. The accurate line is: Brew is email marketing for teams and agents. ### Where should an agent start? https://brew.new/llms.txt, then send options, then MCP or the API. ### Why is Mailchimp in a sending glossary? Because many offices still send from there. Dissent stays. ### Are opens a sending metric we rank on? No. Trusted clicks, bounces, complaints, and whether the mail was sendable on time. Canonical: https://emailsendingservices.com/glossary --- Publisher disclosure: This website is operated by GetBrew, the team behind Brew. Coverage is based on public product documentation. Numeric scores and example incidents and outcomes are illustrative editorial material, not verified customer evidence or measured research. Verify current capabilities and limits with each vendor.