Setting up reply relays

When to use this guide: Use this guide when you want OutboundSync to loop a sales rep into a prospect reply automatically — without the rep sending the first follow-up manually from the SEP.

A reply relay is a Destinations capability for Smartlead and EmailBison. When a prospect replies, OutboundSync sends a reply from the sequencer mailbox and CCs one sales-rep address so the rep can pick up the thread.

This is different from:

• Additional Endpoints — URL forwarding to Clay, Zapier, Make, or a custom endpoint
• Manual SEP reply + CC — a rep sends from the SEP inbox and CCs the rep’s primary address (see Where to reply)

CRM sync stays immediate. The sequencer reply and CC run after the delay configured on the reply relay.

Prerequisites

1. Destinations enabled on the CRM connection. If Destinations is off, the catalog and webhook bind UI tell you to enable it — contact OutboundSync or your onboarding contact; it is not a self-serve toggle on the webhook.
2. A Smartlead or EmailBison webhook receiver for that connection. Instantly and other platforms are not supported for reply relays.
3. A valid SEP API key on that webhook (EmailBison also needs its base URL). Binding a relay without an API key is blocked.

Create a reply relay

1. In OutboundSync, open Connected accounts → Reply relays.
2. Choose a connection that has Destinations enabled.
3. Click Add Reply relay and fill in:

Field	Required	Notes
Description	Yes	Catalog and bind label (for example, AE reply relay — ACME)
CC email	Yes	The mailbox that receives the transferred conversation
Body variations	No	Up to 5 short variants; blank is fine (CC-only). One variant is chosen at send time. Presets cover looping in a colleague or transferring to another inbox.
Send delay	Yes	ASAP, or 1 minute through 4 hours (default 1 minute)
API key for categories	No	Loads Smartlead/EmailBison category or tag options only. Not stored on the relay — Reply-CC uses the webhook’s API key at send time. Required in the UI before you can pick categories/tags.
Apply to lead categories / tags	No	Empty = all replies. When set, after the send delay Reply-CC checks the lead’s current Smartlead category or EmailBison tags and continues only on a match.

4. Click Create.

Create form on Connected accounts → Reply relays. Category/tag options load only after you pick an API key for categories.

You can delete a relay that is not bound to a webhook. There is no edit form in the catalog — create a new relay if you need different settings (including a different category/tag allowlist), then rebind it on the webhook.

Optional category / tag allowlist

Leave Apply to lead categories / tags empty to hand off on every eligible prospect reply (still subject to the once-per-campaign handoff below).

When you select categories or tags:

• Smartlead uses lead categories; EmailBison uses tags (same catalog field).
• After the send delay, OutboundSync looks up the lead’s current category/tags with the webhook’s API key and continues only on a match.
• The catalog Categories column shows the selected names, or All when the allowlist is empty.

Catalog Categories column: All means no allowlist; named values are the selected Smartlead categories or EmailBison tags.

There is no edit form — to change the allowlist, create a new catalog row and rebind it.

Bind the relay on a webhook

1. Open the Smartlead or EmailBison webhook receiver settings.
2. Under Reply relay (optional), choose the catalog row (description (ccEmail)), or None to leave it unbound.
3. Confirm the webhook has a platform API key. If a relay is selected without a key, OutboundSync shows: Reply relay needs a Smartlead/EmailBison API key on this webhook.
4. Save the webhook.

Bind one catalog row under Reply relay (optional) on the Smartlead or EmailBison webhook receiver.

After save, the webhook map shows a separate REPLY RELAY path alongside the CRM mapping.

One reply relay can be bound per webhook.

What happens on a prospect reply

1. The SEP delivers the prospect reply to your OutboundSync webhook.
2. OutboundSync syncs the reply to your CRM immediately.
3. After the catalog send delay, if the relay has a non-empty category/tag allowlist, OutboundSync looks up the lead’s current Smartlead category or EmailBison tags via the webhook API key. No match (or a failed lookup) skips the handoff — status skipped, not failed.
4. When the allowlist check passes (or the allowlist is empty), OutboundSync calls the SEP reply API:
   • From the sequencer mailbox on the reply event (never the connection-owner email)
   • CC the address on the bound reply relay
   • With an optional short body (or blank for CC-only)
5. The SEP may echo that outbound reply into CRM as a sent email with the CC preserved. That echo does not fire another reply relay.

What happens on a second reply

A reply relay is a one-time handoff per webhook + campaign + prospect. The first prospect reply in a campaign can trigger the sequencer reply + CC. Later replies from that same prospect in that same campaign on the same webhook do not send another automated “passing this to my colleague” message. The same prospect in a different campaign can still get a separate handoff.

Those later same-campaign replies still sync to your CRM immediately, so reps and workflows keep seeing activity there (and often via email threading if the prospect uses Reply-All on the CC’d thread). In History → Reply relay logs, the handoff skip is recorded as skipped — not failed. That means the relay already used its handoff for that campaign; it is expected product behavior, not an outage.

Optional automation for “another reply arrived after handoff” (for example a platform webhook event) is not part of this guide and may ship later.

Troubleshooting

Use History → Reply relay logs to inspect recent sends (last 30 days). Filter by webhook, status (success / failed / skipped), platform, or reply relay, and open a row for the raw log payload. The Categories column prefers live lead category/tag names recorded at send time; otherwise it shows Allowlist: … or All.

Logs distinguish a successful handoff from an allowlist miss (skipped, with the reason in Error).

Common reasons a relay does not send:

• Destinations is not enabled on the connection
• No reply relay is bound on the webhook
• Missing or invalid SEP API key (or EmailBison base URL)
• CC address matches the sequencer From or the prospect (self-CC / prospect-CC skips)
• Category/tag allowlist miss — status skipped; the Error column shows the reason; the opened log JSON has error.code category_allowlist_miss
• Category/tag lookup failed (missing lead id, EmailBison base URL, or SEP error) — status skipped; error.code category_lookup_failed
• Per-campaign handoff already used (at most 1 reply-relay attempt per webhook + campaign + prospect) — status skipped, not failed. The handoff counter increments when the job is enqueued, so an allowlist miss or lookup skip still counts as the handoff for that campaign and prospect on that webhook.

Next step

• HubSpot: Where to reply after the loop-in
• Salesforce: Where to reply after the loop-in

Related guides

• Webhook forwarding with Additional Endpoints
• Smartlead webhook guide
• EmailBison webhook guide
• Where to reply: HubSpot vs your sales engagement platform
• Where to reply: Salesforce vs your sales engagement platform
• How to check OutboundSync logs