Thanks for signing up.
"); await mailerSend.email.send(emailParams); ``` **Reloop** ```typescript const reloop = new Reloop({ apiKey: process.env.RELOOP_API_KEY! }); const { response, emailError } = await reloop.mail.send({ from: "AcmeThanks for signing up.
", }); ``` Reloop returns errors as values instead of throwing. Other differences: | | Reloop | MailerSend | |---|---|---| | Request style | Plain object | Builder (`EmailParams`, `Sender`, `Recipient`) | | Error format | `message`, `why` and `fix` | `message` and `errors` | | Template variables | `{{{first_name}}}` | `{{first_name}}` (personalization) | | Recipients per email | `to`, `cc`, `bcc` | Up to 50 | | Webhook signature | `Reloop-Signature` (HMAC-SHA256) | `Signature` (HMAC-SHA256) | | Event names | `email.delivered`, `email.bounced`, … | `activity.delivered`, `activity.hard_bounced`, … | Reloop's error shape is the one strong opinion here. When a send fails, the error says **why** and **how to fix it**: ```json { "message": "Domain not found", "why": "The domain mail.acme.com was not found or is not authorized for your organization", "fix": "Ensure the domain is registered and verified in your dashboard" } ``` MailerSend's docs are thorough and it ships SDKs for seven languages plus an OpenAPI collection, so you won't be short of examples. --- ## Receiving email and agent inboxes **MailerSend** has inbound routing on its paid plans. Incoming mail is parsed and forwarded as JSON to your webhook, or forwarded to another address, with rules by recipient, domain or header. MailerSend doesn't store it as a mailbox, and each forward counts against your monthly email quota. **Reloop** receives mail into **mailboxes**. Messages are stored, threaded, spam-scored with Rspamd, and readable over the API, the [MCP server](/docs/integrations/ai-tools/mcp-server) or IMAP. You can reply in-thread with one call, and there's an `email.received` webhook if you want push notifications too. That matters if you're building: - **AI agents that handle email.** Give an agent its own address, let it read the thread and reply. See [build an AI agent that reads and replies to email](/blog/build-ai-agent-sends-emails). - **Support or shared inboxes** where humans and agents work the same threads. - **Reply handling** for transactional mail ("reply to this email to comment"). | | Reloop | MailerSend | |---|---|---| | Receive on your domain | Yes | Yes (paid plans) | | Stored mailboxes with threads | Yes | No | | Reply in thread via API | Yes | Build it yourself | | IMAP access | Yes | No | --- ## Templates, marketing and automations MailerSend is strong on the visual side. It has a drag-and-drop builder, a rich-text editor, an HTML editor, and split testing. Non-developers can build and edit templates without touching code. Reloop's templates are code-first: store HTML or a React Email component, send it by ID, and fill in `{{{variables}}}`. There's no drag-and-drop builder today. On marketing, MailerSend focuses on transactional mail and points marketing teams to its sister product, MailerLite. Reloop has it in one place: contacts with custom properties, groups, subscription channels, scheduled broadcast campaigns, and **event-triggered automations** with delays, conditions and email steps. See [welcome sequences that convert](/blog/welcome-email-sequences-that-convert) for a worked example. --- ## Deliverability Deliverability comes down mostly to your domain setup and list hygiene. Both handle SPF, DKIM and DMARC setup, bounce and complaint events, open and click tracking, and suppression lists. The differences: - **Dedicated IPs.** Reloop includes one on Growth ($20/mo). MailerSend offers a dedicated IP add-on on Professional, recommended for more than 100k emails a week. - **Monitoring.** MailerSend includes DMARC monitoring and blocklist monitoring on Starter and Professional. Reloop ships free [domain reputation](/tools/domain-reputation-checker), [blocklist](/tools/blocklist-checker) and [auth](/tools/auth-checker) checkers. - **Sending path.** Reloop runs its own MTA (KumoMTA) with per-domain throttling and automatic pauses when bounce or complaint rates spike. Read [how bounce processing works](/blog/email-bounce-processing-automation). --- ## Self-hosting and lock-in MailerSend is hosted-only. Your templates, logs and suppression lists live in its database, and activity data is kept for 1 to 30 days depending on plan (longer is a paid add-on). Reloop is Apache 2.0. You can: 1. Start on Reloop Cloud. 2. Move to your own server later with the [one-command installer](/self-host) or [Coolify](/blog/reloop-coolify-setup). 3. Keep the same API. Point the SDK's `baseUrl` at your instance and nothing else in your code changes. That helps with data residency, security reviews that need to read the code handling your users' mail, and insurance against price changes. Self-hosting does mean you own IP reputation, warm-up and uptime, so most teams start hosted. --- ## Where MailerSend is the better choice - **Non-developers edit your emails.** The drag-and-drop builder and template editors are more complete than anything Reloop offers. - **You need SMS** alongside email, or built-in email verification and split testing, from one vendor. - **You already use MailerLite** for marketing and want the sister product for transactional mail. ## Where Reloop is the better choice - **Cost matters past a few thousand emails.** $10 vs $35 at 50k, $20 vs $68 at 100k. - **You need inbound mail as real inboxes**, especially for AI agents. - **You want transactional mail, campaigns and automations** in one product with one suppression list. - **You need open source or self-hosting.** --- ## Switching from MailerSend to Reloop 1. **Add your domain in Reloop** and publish the DKIM record (`reloop._domainkey`). Merge `include:reloop.sh` into your existing SPF record rather than adding a second one. 2. **Swap the client.** Replace the `EmailParams` builder and `mailerSend.email.send` with a single `reloop.mail.send` call. 3. **Move templates.** Change personalization placeholders to triple braces: `{{first_name}}` becomes `{{{first_name}}}`. 4. **Export your suppression list** from MailerSend and import it into Reloop, so you never mail an address that bounced or complained. 5. **Point webhooks** at a new handler. Map `activity.delivered` → `email.delivered`, `activity.hard_bounced` → `email.bounced`, `activity.spam_complaint` → `email.complained`, and verify the `Reloop-Signature` header instead of `Signature`. 6. **Move inbound routes** to a Reloop mailbox, or keep using a webhook with `email.received`. 7. **Ramp traffic** from 10% to 100% over a week or two, then remove MailerSend's DNS records. Our [SendGrid migration guide](/blog/migrating-from-sendgrid) walks through the traffic split and suppression import in more detail; the same steps work from MailerSend. --- ## FAQ