Follow-up Sequences

Sequences define automated follow-up emails that trigger based on recipient behavior. Each follow-up step has its own email variants.

Sequences are the campaign’s MAIN follow-up chain — the linear path every lead takes. Conditional branches that pull a lead off that path are subsequences, managed through a separate set of endpoints. Nothing on this page creates, edits or removes a branch.

How Sequences Work

Initial email is sent to lead
ColdSend waits the configured number of days
If the trigger condition is met, follow-up is sent
Process repeats for subsequent steps

Campaign Status and Sequence Updates

Sequences can be managed differently depending on campaign status:

Status	Field	Behavior	Use Case
DRAFT	`sequences`	Replaces all sequences at once	Initial campaign setup
PAUSED	`sequence_edits`	Granular add/edit/delete per sequence	Update copy on running campaigns

sequences and sequence_edits are mutually exclusive — you cannot use both in the same request. Using sequences on a PAUSED campaign returns a 400 error, and sequence_edits on a DRAFT campaign also returns a 400 error.

Configuring Sequences (DRAFT campaigns)

Use the sequences array to replace all follow-up sequences at once. This is the simplest approach during initial campaign setup:

Python

response = requests.put(
    f"{base_url}/api/public/v1/campaigns/{campaign_id}",
    headers={"X-API-Key": api_key},
    json={
        "sequences": [
            {
                "step_number": 2,
                "trigger_type": "NOT_OPENED",
                "wait_days": 3,
                "variants": [
                    {
                        "variant_name": "A",
                        "subject_template": "Following up on my previous email",
                        "email_content": "Hi {{first_name}},\n\nI wanted to follow up on my previous email...\n\nBest,\nJohn",
                        "distribution_percent": 100
                    }
                ]
            },
            {
                "step_number": 3,
                "trigger_type": "NOT_REPLIED",
                "wait_days": 5,
                "variants": [
                    {
                        "variant_name": "A",
                        "subject_template": "Last thought",
                        "email_content": "Hi {{first_name}},\n\nOne last thought I wanted to share...\n\nBest,\nJohn",
                        "distribution_percent": 100
                    }
                ]
            }
        ]
    }
)

Sequence Fields

Field	Type	Required	Description
`step_number`	int	Yes	Sequence position (2-11). Step 1 is the initial email.
`trigger_type`	string	Yes	When to send: `NOT_OPENED`, `NOT_REPLIED`, or `OPENED_BUT_NOT_REPLIED`
`wait_days`	int	Yes	Days to wait (1-30)
`enable_unsubscribe`	bool	No	Override campaign setting. Inherits if not specified.
`variants`	array	Yes	At least one email variant required per sequence

Trigger Types

Trigger	Fires When
`NOT_OPENED`	Lead has not opened any previous email
`NOT_REPLIED`	Lead has not replied to any email (includes those who opened but didn’t reply)
`OPENED_BUT_NOT_REPLIED`	Lead opened at least one email but hasn’t replied

NOT_REPLIED is the most commonly used trigger — it reaches both non-openers and openers who didn’t respond.

These three values are valid only on the MAIN chain. A subsequence branch takes INTENT_TAG, KEYWORD or STATUS as its entry trigger and rejects these with a 422 — the two vocabularies do not overlap.

Sequence Limits

These are enforced by the API and return a 422 when violated:

Limit	Value
Step numbers	2 through 11 — step 1 is the initial email, so up to 10 follow-ups
Wait days per step	1–30 days
Variants per step	At least 1

The total span of a chain is therefore whatever your step waits add up to; there is no separate campaign-duration cap at the API level.

Sequence Edits (PAUSED campaigns)

For PAUSED campaigns, use sequence_edits to modify individual sequences without replacing everything. Each item has an action field:

Python
JavaScript

response = requests.put(
    f"{base_url}/api/public/v1/campaigns/{campaign_id}",
    headers={"X-API-Key": api_key},
    json={
        "sequence_edits": [
            {
                "action": "add",
                "step_number": 3,
                "trigger_type": "NOT_REPLIED",
                "wait_days": 5,
                "variants": [
                    {
                        "variant_name": "A",
                        "subject_template": "One more thought",
                        "email_content": "Hi {{first_name}},\n\nOne last thing I wanted to share...\n\nBest,\nJohn",
                        "distribution_percent": 100
                    }
                ]
            },
            {
                "action": "edit",
                "sequence_id": "existing-sequence-uuid",
                "variants": [
                    {
                        "variant_name": "A",
                        "subject_template": "Updated subject",
                        "email_content": "Updated follow-up content...",
                        "distribution_percent": 100
                    }
                ]
            },
            {
                "action": "delete",
                "sequence_id": "sequence-to-remove-uuid"
            }
        ]
    }
)

const response = await fetch(`${baseUrl}/api/public/v1/campaigns/${campaignId}`, {
  method: "PUT",
  headers: {
    "X-API-Key": apiKey,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    sequence_edits: [
      {
        action: "add",
        step_number: 3,
        trigger_type: "NOT_REPLIED",
        wait_days: 5,
        variants: [{
          variant_name: "A",
          subject_template: "One more thought",
          email_content: "Hi {{first_name}},\n\n...",
          distribution_percent: 100
        }]
      }
    ]
  })
});

Sequence Edit Actions

Action	Required Fields	Description
`add`	`step_number`, `trigger_type`, `wait_days`, `variants`	Create a new follow-up sequence
`edit`	`sequence_id`, + any fields to update	Modify an existing sequence (partial update)
`delete`	`sequence_id`	Remove a sequence entirely

Use GET /campaigns/{campaign_id} to retrieve existing sequence_id values before editing or deleting.

Best Practices

Recommended Timing

Step	Recommended Wait	Purpose
2 (first follow-up)	2-4 days	Reference original email, add value
3 (second follow-up)	5-7 days	Offer a case study or specific resource
4 (final follow-up)	7-10 days	Create urgency or breakup email

Subject Line Patterns

Approach	Example
Reference previous	`Re: Quick question about {{company}}`
Fresh angle	`One more thing about {{company}}`
Curiosity	`Did you see this?`

Next Steps

Subsequences

Branch a lead off the main chain when they reply, get tagged, or change status.

Email Variants

A/B testing and personalization for follow-ups.

Personalization

Use variables, spintax, and conditionals.

Getting Started

Authentication

Campaigns

Sender Accounts

Domains

Contacts

Leads

Replies

Analytics

Webhooks

Reference

Compliance

How Sequences Work

Campaign Status and Sequence Updates

Configuring Sequences (DRAFT campaigns)

Sequence Fields

Trigger Types

Sequence Limits

Sequence Edits (PAUSED campaigns)

Sequence Edit Actions

Best Practices

Recommended Timing

Subject Line Patterns

Next Steps

Subsequences

Email Variants

Personalization

​How Sequences Work

​Campaign Status and Sequence Updates

​Configuring Sequences (DRAFT campaigns)

​Sequence Fields

​Trigger Types

​Sequence Limits

​Sequence Edits (PAUSED campaigns)

​Sequence Edit Actions

​Best Practices

​Recommended Timing

​Subject Line Patterns

​Next Steps

Subsequences

Email Variants

Personalization

How Sequences Work

Campaign Status and Sequence Updates

Configuring Sequences (DRAFT campaigns)

Sequence Fields

Trigger Types

Sequence Limits

Sequence Edits (PAUSED campaigns)

Sequence Edit Actions

Best Practices

Recommended Timing

Subject Line Patterns

Next Steps