Audience
Custom Fields are the typed properties on each contact — text, number, date, dropdown, and more — referenced as %%field%% merge tags. They power personalization, segmentation, conditional content, and conversion attribution. The backbone the rest of the platform stands on.
Hi Ada, your Pro plan renews on Mar 14.
← from %%first_name%%, %%plan%%, %%renews_on%%
Pick the right shape
Each field declares its type, so the data stays clean on the way in and gets the right operators on the way out. The type isn't cosmetic — it's what makes segmentation and validation work.
Names, cities, identifiers — short single-line values.
Longer free text — notes, addresses, descriptions.
MRR, order count, score — filter with greater-than / less-than.
Signup, renewal, last order — filter with before / after / within.
Pick-one from a defined list — plan, tier, region.
Pick-one as visible options — preference, status.
Yes/no flags and multi-select interests.
More field types are added over time — the model isn't fixed to this set.
Why typing matters
A store that treats everything as text can only match exact strings. Typed fields turn stored data into targeting power — the same reason a spreadsheet column has a format.
Typed field
A field that knows it's a date can be filtered with "renews in the next 7 days". One that knows it's a number can drive "MRR over $500". Typing unlocks range, comparison, and date operators in segmentation — and validates the data on the way in.
Free-text blob
An untyped store can only ask "does this exactly equal that string?". No "greater than", no "before this date", no validation. The data drifts — "Pro", "pro", "PRO " all become different values — and targeting falls apart.
One template, every recipient
Drop %%field_name%% into the subject, pre-header, or body and each recipient sees their own value at send time — with a fallback you set for anyone missing it, so a blank never prints an awkward gap.
It's the simplest of the personalization mechanisms — and the one the others build on. Spintax rotates phrasing, Dynamic Content Tags swap whole blocks, but it all starts with the field values on the contact.
Template
Resolves to
The backbone
Custom Fields aren't a standalone feature — they're the substrate. Three of the things you do most depend directly on what's stored on the contact.
Merge the value
Every %%field%% in a subject, pre-header, or body resolves per recipient. Rich fields mean a message that reads like it was written for one person.
Filter the audience
You are hereSegments are queries over fields. Type-aware operators — greater-than, before/after, contains — turn stored data into precise, dynamic audiences.
Branch the message
Dynamic Content Tags swap whole blocks on a field value — show one hero to Pro customers, another to Free. One send, the right version for each.
What teams build with fields
“We moved everything onto typed fields and it changed how we send. “Renews in 7 days”, “MRR over $500 and hasn't opened in 30” — those segments just weren't buildable when our data was a pile of text columns. Now they run themselves.”
Verified review
Mumara ONE customer
Common questions
Text, multiline text, number, date, dropdown, radio, and checkbox — with more added over time. The type determines both how the value is stored and validated, and which operators are available when you segment on it (for example, before/after on dates, greater-than on numbers).
Reference it as %%field_name%% in the subject, pre-header, or body. At send, each recipient's value is merged in, with a fallback you set for contacts missing that value — so a blank never prints an awkward gap.
Web forms, landing-page forms, CSV import with column mapping, the REST API, and trigger actions can all write to fields — so the contact record builds and updates itself across every touchpoint, not just at import.
Because segmentation operators depend on it. A date field unlocks "before / after / within N days"; a number field unlocks "greater than / less than"; a dropdown keeps values consistent so "equals Pro" actually matches. Free text can only do exact-string matching, and the data drifts ("Pro" vs "pro" vs "PRO ").
Yes. Dynamic Content Tags branch whole blocks on a field value, spintax can key off fields, and the Mumara AI composer can reference them — the field value on the contact is the common input all the personalization mechanisms read from.
Define the type when you create the field, since stored values and segment operators depend on it. If you need to change how data is shaped, the cleanest path is to add a new typed field and migrate values into it — so existing segments and merges don't silently break.
You can model as much per-contact data as your use case needs — add fields as your segmentation and personalization get more sophisticated. The record grows with you rather than capping at a fixed schema.
Related
Fields are what segments filter on, with operators determined by each field's type.
Read moreConditional blocks branch on field values to render different content per recipient.
Read moreField merges are the foundation the spintax, conditional, and AI layers build on.
Read moreForm fields map straight to Custom Fields, so capture and storage are one step.
Read moreFields live on the contact record inside the lists/contacts/fields data model.
Read moreMumara ONE · Custom Fields
Typed profile fields merge into messages, filter your segments, branch your content, and tie changes back to revenue. The foundation the rest of the platform stands on.
