Every feature that makes Mailers.io a control plane, not an email tool
Mailers.io is the orchestration layer that sits on top of the email providers you already use. One dashboard, one API, and a serious operating system for outbound email — routing, campaigns, automations, compliance, and team governance in a single platform.
- Provider drivers
- 19+Provider drivers
- Across every provider
- 1 APIAcross every provider
- Resource groups for RBAC
- 7Resource groups for RBAC
- You own the sending stack
- 100%You own the sending stack
Eight chapters, one platform.
Jump to any capability. Every feature below ties back to one truth — Mailers.io is the control layer on top of the providers, domains, and sending infrastructure you already own.
Orchestration & Routing
- Multi-provider sending
- Quota-aware routing
- Sending servers
- Sending domains
Developer Platform
- Unified sending API
- Webhooks & events
- Analytics API
Campaigns & Automation
- Campaigns
- Automations
- Sequences
- Templates
Audience Management
- Mail lists
- Segmentation
- Forms
- Subscriber API
Compliance & Governance
- Suppression lists
- List-unsubscribe
- Audit logs
- Do-not-contact
Teams & Access Control
- Custom roles
- Resource-level permissions
- Workspaces
- SSO & SCIM
Operational Control
- Quotas & caps
- Priority weighting
- Fallback rules
- Health monitoring
Integrations
- SES, Mailgun, SendGrid, Resend
- SMTP servers
- Gmail & Microsoft 365
Multi-provider sending, one platform in front of all of them
Connect the providers you already use — Amazon SES, Mailgun, SendGrid, Resend, Postmark, Brevo, Gmail, Microsoft 365, or any SMTP server. Mailers.io unifies them behind a single API and dashboard so your team can operate outbound email without managing N separate integrations.
Why multi-provider
- Connect unlimited provider accounts per workspace
- Mix API-native and SMTP providers in the same pool
- Add new providers without changing application code
- Isolate providers per client, brand, or use case
Key truth
You keep your provider accounts, your domains, and your sending reputation. Mailers.io is the control layer on top — no lock-in, no reselling, no hidden infrastructure.
API-native providers
10 driversSMTP & OAuth
5 driversNeed another provider? SMTP covers nearly every sending service. For API-native connectors, new drivers ship on a regular cadence.
Routing that respects every provider's limits
The core of Mailers.io. You configure the rules once — caps, priorities, fallbacks — and the platform enforces them on every send. No wrapper scripts, no custom failover logic, no 3 AM pages when SES throttles you.
Per-provider quota caps
Set hourly and daily limits per provider. Mailers.io enforces them on every send — no provider is pushed past its threshold.
Health-aware routing
Bounce spikes, complaint surges, or soft failures shift traffic away from degraded providers in real time.
Priority & weight
Pin preferred providers, balance by weight, or drain specific accounts during warm-up windows.
Automatic fallback
When a provider is over quota or unhealthy, routing shifts instantly to the next eligible pool member.
Routing pool · acme-prod
Current hour usage across providers
Routing decision · POST /v1/send
// SendGrid above 85% for this window → skip: sendgrid (throttling) // SES below cap, priority = 1 → pick: amazon-ses (eligible) → server: aws-prod-01 → result: 202 accepted in 38ms
Every sending server, operated from one console
A sending server is the concrete endpoint email leaves from — an SES sub-account, a Mailgun domain, an SMTP host, or an OAuth-connected Gmail. Mailers.io treats them as first-class objects you can name, scope, and govern.
Named sending servers
Register one or more sending servers per provider account. Give each one a clear name, scope, and owner — aws-prod-us, mailgun-cold-eu, smtp-ops-internal.
Routing eligibility rules
Whitelist which campaigns, workspaces, or API keys can send through a server. Keep transactional reputation isolated from outbound campaigns.
Warm-up and ramp controls
Gradually ramp a new server into the pool with custom hourly and daily caps. Rotate older servers out without interrupting sending.
Health & status signals
Live status per server — active, throttling, paused, or unhealthy. Auto-remove unhealthy servers from routing until they recover.
Workspace · acme-prod · Sending servers
5 serversaws-ses-prod-us
Amazon SES · us-east-1
mailgun-campaigns-eu
Mailgun · eu-central
sendgrid-lifecycle-v2
SendGrid · global
smtp-warmup-resend
Resend · global
smtp-postfix-fallback
Custom SMTP · internal
Own every sending domain, down to the DNS
Domains are how deliverability actually works. Mailers.io lets you register every domain you send from, verify DKIM and SPF per provider, and scope suppression and reporting at the domain level.
- DKIM signing per provider
- SPF alignment with connected senders
- DMARC policy enforcement
- Return-path / bounce domain setup
- Per-domain suppression scope
- Per-domain analytics segmentation
Operational separation
Transactional, lifecycle, and cold outbound should not share reputation. Domains in Mailers.io are independent objects — you decide which campaigns, automations, and API keys can touch each one.
acme.com · DNS verification
verifiedmail._domainkey.acme.com
v=DKIM1; k=rsa; p=MIIBIjANBg...
acme.com
v=spf1 include:amazonses.com include:mailgun.org -all
em123.acme.com
u12345.wl.sendgrid.net
A single API across every connected provider
Mailers.io is API-first. Everything you can do in the dashboard — sending, campaigns, lists, suppression, domains, analytics — is available through the same REST interface. Integrate once, swap providers forever.
One API for every provider
Write against /v1/send once. The router decides which connected provider to use based on your rules — your code never needs a branch.
Scoped API keys
Issue keys per service or environment. Scope them to specific workspaces, domains, or actions. Rotate without downtime.
Predictable, stable contracts
Normalized request and response shape. Provider-specific quirks are handled behind the interface, not leaked to your app.
curl -X POST https://api.mailers.io/v1/send \
-H "Authorization: Bearer $MAILERS_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"from": "[email protected]",
"to": "[email protected]",
"subject": "Welcome to Acme",
"html": "<p>Thanks for joining.</p>",
"tags": ["onboarding"]
}'p95
38ms
regions
3 pops
uptime
99.95%
Every send, normalized into one event stream
Each provider emits events in its own shape. Mailers.io normalizes them into a single schema — so your pipelines, CDPs, and dashboards don't care whether the message left via SES, Mailgun, or SendGrid.
Webhook delivery
Signed HTTPS payloads, retry with exponential backoff, dead-letter visibility.
Event subscriptions
Subscribe to specific event types, workspaces, domains, or campaign IDs.
Unified analytics
Delivery, open, click, bounce, and complaint rates per domain, campaign, or provider — comparable across your whole stack.
Event catalog
8 normalized typeslive stream · /v1/events
streaming- 15:42:11email.deliveredamazon-ses[email protected] · 38ms
- 15:42:09email.sentamazon-sesmessage_id=m_9af21
- 15:42:04email.openedmailguncampaign=cmp_onboard
- 15:42:01email.bouncedsendgridhard · auto-suppressed
- 15:41:57email.clickedmailgunlink=pricing
Campaigns built for teams, routed through your own stack
Compose, schedule, and ship email campaigns with clear controls and a reporting view that treats every connected provider as first-class data.
Segment before you send
Pull recipients from any mail list, filter by tag, subscription date, or custom field. Preview counts before launch.
Schedule and throttle
Send immediately, schedule for a later window, or spread a campaign across hours to stay inside provider quotas.
Routed through your pool
Campaigns route through the same quota-aware pool as the API. No separate sending stack, no surprises.
Per-campaign reporting
Delivered, opened, clicked, bounced, complained, unsubscribed — broken down by provider and recipient domain.
Campaign · Q1 re-activation
cmp_q1_reactivate · scheduled 09:00 UTC
Recipients
48,312
Delivered
47,619
98.6%
Opens
21,744
45.6%
Clicks
4,912
10.3%
Bounces
693
1.4%
Unsubs
128
0.26%
Routed through
Event, time, and condition-based automations
Build outbound sequences, lifecycle flows, and re-engagement journeys without stitching together cron jobs and worker queues. Every automation runs on the same routing and compliance layer as your direct API sends.
Event-based
Triggered by API calls, form submissions, subscriber tags, list membership, or webhook events from your product.
Time-based
Fire on subscriber anniversaries, after delays, at specific times, or on recurring schedules. Respect per-recipient timezones.
Condition-based
Branch on any subscriber attribute, tag, event history, or engagement signal. Build logic without writing custom workers.
Automation · onboarding_v3
Live flow · 2,411 subscribers in progress · 0 errors
Every sent message inside an automation honors the same suppression rules, domain-level controls, and routing pool as a direct API send. One source of truth — not duplicate infrastructure per workflow.
One template library, reused by every team and every send
Versioned, auditable templates that power campaigns, automations, and API sends from the same source of truth. No more one template in Mailchimp, another in SES, a third hardcoded in your product.
Handlebars-style variables
Interpolate subscriber fields, list attributes, and custom variables with a safe template syntax.
HTML, MJML, or plain-text
Bring your existing MJML layouts, paste raw HTML, or build in the editor. Plain-text alternatives are generated automatically.
Localized variants
Ship multiple language versions of one template, selected per recipient at send time.
Template library
6 of 42 shownwelcome.onboarding
Updated 2d ago
en, es, dev3trial.expiring
Updated 5d ago
env7invoice.receipt
Updated 1w ago
en, frv12cold.outreach.saas
Updated 3d ago
env4renewal.reminder
Updated 2w ago
en, esv2password.reset
Updated 6h ago
en, de, fr, esv9
Mail lists, segments, and subscriber data you own
Your audience is yours. Mailers.io gives you the tooling to import, segment, and govern it — but we don't resell contacts and we don't bundle a lead database. You bring subscribers, we keep them addressable.
Lists · workspace acme-prod
12 lists- 18,420
Product waitlist
waitlistprelaunch - 32,118
Active customers
customermrr - 4,612
Trial users · last 30d
trialonboarding - 12,980
Q1 outbound · agencies
coldagency
Segment · high-intent US trials
Segments are live filters — not static copies. When subscriber attributes change, segment membership updates in place.
Bulk import
CSV imports with column mapping, deduplication, and automatic validation against your suppression and bounce lists.
Subscriber API
Push subscribers from your product in real time. Sync tags, fields, and list membership programmatically.
Forms
Hosted or embedded sign-up forms land subscribers directly in the list you choose, with double opt-in if required.
Subscriber collection without a separate tool
Capture opt-ins from landing pages, product flows, and marketing sites. Mailers.io forms land subscribers into the right list, respect compliance rules, and trigger automations on submit.
- Hosted form pages on your domain
- Embeddable script or iFrame widgets
- Single or double opt-in flow
- Custom fields mapped to subscriber data
- reCAPTCHA / hCaptcha support
- Automatic suppression-list enforcement
Embed anywhere
Static sites, Webflow, WordPress, custom SPAs.
Compliance-first
Suppression, consent timestamps, IP logged for audit.
Stay in the loop
Product updates, monthly
One honest email a month. No fluff, no filler. Unsubscribe any time.
Suppression, governance, and audit as first-class citizens
Compliance is not a feature flag or a downstream checkbox. Every send in Mailers.io passes through a layered suppression pipeline, and every action is written to an audit log your team and auditors can actually use.
Global suppression
Any address added here is blocked across every list, campaign, automation, and API send in the workspace.
Domain suppression
Scope suppressions to a single sending domain when you want to silo reputation per product or brand.
List unsubscribe
Opt-outs recorded on a specific list; enforced for all sends scoped to that list.
Bounce & complaint suppression
Hard bounces, spam complaints, and provider-reported failures auto-added to the suppression layer.
Do-not-contact registry
Enterprise DNC entries from procurement, legal, or customer requests — honored across every send path.
Send-time checks
- List-Unsubscribe headerenforced
- One-click unsubscribe (RFC 8058)enforced
- Consent timestampsenforced
- IP + user-agent loggedenforced
- DKIM / SPF per domainenforced
- DMARC reportingenforced
Audit logs
Every action — config change, API key issued, campaign launched, subscriber suppressed — is recorded with actor, IP, and timestamp. Export via API or stream to your SIEM.
Data residency
You control which region providers run in. Subscriber data is segregated per workspace.
No magical deliverability
We don't claim inbox guarantees. We give you the controls serious operators need.
Encryption in transit & at rest
TLS 1.2+ on every hop. Provider credentials encrypted. Scoped API keys, rotatable on demand.
Custom roles, real RBAC, zero all-or-nothing admin access
Agencies, in-house growth teams, and platform teams all share the same pain — too many people with too much access. Mailers.io lets you define custom roles with Full Access or Read Only permissions per resource group, plus workspace isolation for multi-client setups.
| Resource group | Owner | Admin | Operator | Analyst | Read Only |
|---|---|---|---|---|---|
| Campaigns | Full | Full | Full | Read | Read |
| Mail Lists | Full | Full | Full | Read | Read |
| Automations | Full | Full | Full | Read | Read |
| Templates | Full | Full | Full | Read | Read |
| Forms | Full | Full | Full | Read | Read |
| Sending Servers | Full | Full | Read | — | — |
| Sending Domains | Full | Full | Read | — | — |
| Billing & Plan | Full | Read | — | — | — |
Workspace isolation
Separate workspaces per client, brand, or environment. Providers, domains, and subscribers live inside a workspace — not across the whole account.
Invitations & revocation
Invite by email. Revoke a seat instantly. Every invitation, role change, and revocation writes an entry in the audit log.
Scoped API keys
API keys inherit scopes too. Issue a key that can only send, only read analytics, or only manage subscribers — and tie it to a specific workspace.
Connect what you already run. Keep your sending infrastructure.
Mailers.io is provider-agnostic. If you have an account with it, you can probably connect it. SMTP covers almost everything that isn't API-native.
Amazon SES
- ·API + SMTP
- ·Multi-region (us-east-1, eu-west-1, ap-*)
- ·Sub-account support
- ·Event forwarding via SNS
Mailgun
- ·US & EU regions
- ·Per-domain sending
- ·Tag-based analytics
- ·Webhook ingestion
SendGrid
- ·v3 API
- ·Subusers & IP pools
- ·Click / open tracking
- ·Event webhook
Resend
- ·Modern API
- ·React Email support
- ·Low-latency sending
- ·Event webhook
Postmark
- ·Transactional streams
- ·Inbound parsing
- ·Bounce classification
- ·Broadcast streams
Brevo / SparkPost / Mailjet
- ·API-native drivers
- ·Sub-account routing
- ·Bounce + complaint sync
- ·European data residency options
Gmail / Google Workspace
- ·OAuth connection
- ·Per-mailbox daily caps
- ·Ideal for low-volume cold outreach
- ·No delegated access required
Microsoft 365 / Outlook
- ·OAuth connection
- ·SMTP fallback
- ·Tenant-level controls
- ·Audit trail alignment
Custom SMTP
- ·Any RFC-compliant SMTP server
- ·TLS + STARTTLS
- ·Custom auth types
- ·Internal Postfix / Exim / Halon
Missing a provider you depend on? Custom SMTP handles almost any edge case. For native API drivers, new providers are added on a regular cadence — let us know what you need.
Honest answers about what Mailers.io does and doesn't do
If we don't ship a capability, we say so. Procurement and engineering teams save a lot of time when positioning is precise.
Operate outbound email like infrastructure, not like a patchwork of tools
Connect your providers, configure routing once, and let your team run campaigns, automations, and API sends from the same control plane. No lock-in. No reselling. No hidden infrastructure.
- No credit card required
- Bring your own providers
- Cancel anytime