A suppression list holds enough information to recognise people who have objected to marketing or opted out. The ICO advises using it to screen future lists rather than simply deleting the contact and risking their addition again. Keep only the information needed for that purpose. Source: ICO: respecting marketing preferences

A travel marketing example

Imagine an agency imports a new campaign list that includes a former subscriber. Check it against the relevant suppression records before sending, so an earlier opt-out is respected even though the address has arrived through a different file.

This is a process example, not a claim that a particular email platform performs the check automatically. Verify the behaviour of your own connected systems.

Test the complete route

Use a test contact to unsubscribe, then try the normal import and audience selection process. Confirm that the marketing preference remains effective at the point of sending.

Record which system owns the preference and how changes reach other tools. This gives the team a clear place to investigate if two systems disagree about whether someone should receive a campaign.

Written and updated by Travelgenix. Sources checked on 16 October 2026. Worked examples and checklists are editorial illustrations and recommendations, not customer results.