The legacy address-book system stores names and emails — full stop. The new Contacts system stores names, emails, custom fields, tags, segments, behaviour history, multi-channel preferences (email + SMS) and consent timestamps. Migrating unlocks roughly twice the email-marketing capability with the same effort.
What you gain by migrating
| Capability | Address book | Contacts |
|---|---|---|
| Custom fields | No | Up to 30 per contact |
| Tags | No | Unlimited per contact |
| Segments | No | Visual builder |
| Behavioural targeting | No | Open/click/purchase based |
| Multi-channel (Email + SMS) | Email only | Both |
| Automations | Limited | Triggered by tag, field, behaviour |
| API access | Read-only | Full read/write |
| Per-recipient timezone | No | Yes |
| Consent timestamp + IP | No | Auto-recorded |
What you don’t lose
Migration preserves email, name, opt-in status, subscription date and any custom fields you had. Mailpro adds tags matching your original list names so you can still target the «old» segments by tag. The original address book stays available for export 30 days after migration.
The three real reasons to migrate now
1. Mailbox provider requirements (2024+): Gmail and Yahoo expect engagement-based sending. Without segmentation you can’t consistently meet their thresholds. 2. Compliance: GDPR consent records require timestamps and source — the contacts system records both automatically. 3. Future features: every new Mailpro feature ships for contacts only.
What stops people from migrating
Two myths: «migration breaks my campaigns» (it doesn’t — existing campaigns continue using their assigned address book until you re-target them) and «the new system is harder» (it’s actually simpler — the visual segment builder replaces ad-hoc list duplication).
Migrate when you’re ready — sooner the better
It takes 2–5 minutes per address book and is reversible 30 days. Read the why migrate FAQ and follow the migration guide.