Suppression List

Manage email addresses that are blocked from receiving emails. Addresses are automatically suppressed on hard bounces, spam complaints, and after 3 consecutive soft bounces. Manual entries can also be added via API or dashboard.

The suppression list prevents sending to email addresses that have previously hard-bounced, soft-bounced repeatedly, or received spam complaints. This protects your sender reputation and improves deliverability.

Automatic suppression:

• Permanent bounces — when SES reports a permanent (hard) bounce, all bounced recipient addresses are added with reason "hard_bounce"
• Spam complaints — when a recipient marks your email as spam, their address is added with reason "complaint"
• Repeated soft bounces — after 3 consecutive soft bounces (Transient or Undetermined SES bounce types) from the same address with no successful delivery in between, the address is added with reason "soft_bounce". The counter resets on any successful delivery, so transient mailbox issues don't accumulate forever.

Reason codes:

• hard_bounce — permanent failure (mailbox doesn't exist, domain unreachable)
• soft_bounce — 3+ consecutive transient failures (mailbox full, server temporarily down)
• complaint — recipient reported the email as spam
• manual — added manually by you (via API or dashboard)

Send behavior:

• Before every send (API and SMTP), suppressed recipients are silently filtered out
• If ALL recipients in a request are suppressed, the send fails with an error message listing the suppressed addresses
• CC and BCC recipients are also checked and filtered
• Newsletter and broadcast sends share the same suppression list

Manual management:

• Add addresses manually via the dashboard or API with reason "manual"
• Remove any suppression (auto or manual) to allow sending again — the soft bounce counter is also wiped
• Each suppression is scoped to your workspace — other workspaces are not affected

GET/v1/suppressionsAPI Key

List all suppressed email addresses in the current workspace, ordered by most recently added.

Response

json

[
  {
    "id": "550e8400-e29b-41d4-a716-446655440000",
    "email": "bounced@example.com",
    "reason": "hard_bounce",
    "notes": "smtp; 550 5.1.1 The email account does not exist",
    "created_at": "2026-04-15T10:30:00.000Z"
  },
  {
    "id": "7d24c920-a8eb-22e2-91c5-11d15ec541d9",
    "email": "fullmailbox@example.com",
    "reason": "soft_bounce",
    "notes": "3 consecutive soft bounces — last: 452 4.2.2 Mailbox full",
    "created_at": "2026-04-14T14:22:00.000Z"
  },
  {
    "id": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
    "email": "complained@example.com",
    "reason": "complaint",
    "notes": "abuse",
    "created_at": "2026-04-14T08:15:00.000Z"
  }
]

POST/v1/suppressionsAPI Key

Manually add an email address to the suppression list. Idempotent — adding an already-suppressed address is a no-op.

Parameter	Type	In	Description
`email`required	`string`	body	Email address to suppress (will be lowercased)
`notes`	`string`	body	Optional note explaining why the address was suppressed

Request

bash

{
  "email": "user@example.com",
  "notes": "Requested removal from mailing list"
}

Response

json

{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "email": "user@example.com",
  "reason": "manual",
  "notes": "Requested removal from mailing list",
  "created_at": "2025-06-15T10:30:00.000Z"
}

DELETE/v1/suppressions/:idAPI Key

Remove a suppression entry, allowing the email address to receive emails again.

Parameter	Type	In	Description
`id`required	`string`	path	Suppression entry UUID

Response

json

{
  "success": true
}

SMTP Relay

Sandbox Mode