Email CRM integration

Deciding what syncs

One-way or two-way

A one-way sync sends data from one system to the other; a two-way sync updates both. Two-way is convenient but can cause loops and overwrites if both systems edit the same field. Decide field by field which system is the source of truth, and sync that field in one direction only unless there is a clear reason not to.

Where consent lives

Pick one system as the master record of marketing consent, and make the other follow it. If a contact unsubscribes in the email platform, the CRM must know; if sales records that a client asked not to receive marketing, the email platform must know. ICO guidance says marketing emails to individuals need consent or soft opt-in, so mismatches are a compliance risk as well as an annoyance.

Building an integration

1. 01

   Plan fields

   What, which direction, why.

   Output: Field map

2. 02

   Matching

   How contacts are paired.

   Output: Matching rule

3. 03

   Connect

   Native connector or tool.

   Output: Live sync

4. 04

   Test

   Create, update, unsubscribe.

   Output: Test results

5. 05

   Monitor

   Errors and counts.

   Output: Healthy sync

Matching contacts

Most integrations match contacts by email address. People with several addresses, shared inboxes and typos can create duplicates. Agree what happens when no match is found, whether a new contact is created or the record is skipped, and clean obvious duplicates before connecting.

Example: a B2B consultancy

Integration checks

Sync only what you use

Syncing every field adds clutter and personal data you must look after. Start with the fields that drive segments, follow-up and consent, and add others only when there is a use for them.

Errors and monitoring

Syncs fail quietly when passwords change, fields are renamed or limits are reached. Set up an alert for errors where possible, and compare contact counts in both systems once a month.

How often data moves

Some connections sync almost immediately; others run on a schedule. For unsubscribes, faster is safer, because a delay can mean someone who opted out receives the next campaign. For fields used in segments, a daily sync may be enough. Check the timing your connection offers and plan sends around it.

Using CRM data in emails

Once customer type, stage or account owner reach the email platform, segments can send relevant emails: onboarding for new clients, updates for existing ones, nothing promotional to people in a sensitive stage such as a complaint. Agree with sales or service teams which CRM fields should change what people receive.

Testing the connection

Create a test contact in each system and watch it appear in the other. Update a field, then unsubscribe the contact in each system in turn and confirm the change arrives. Delete the test contacts afterwards.