Migrate from Proton to Mailchimp

Proton Contacts with full name, email address, phone number, physical address, and custom fields map to Mailchimp Audience Members. The primary email address on the Proton Contact becomes the subscriber email. The First Name and Last Name split from the Proton contact name into Mailchimp's FNAME and LNAME merge fields. Any phone number maps to PHONE. Physical address fields map to Mailchimp's address merge field group (ADDRESS, CITY, STATE, ZIP, COUNTRY). Custom fields migrate with truncation to 255 characters where applicable.

Proton Contact custom fields (text, number, date, checkbox) map to Mailchimp merge fields. Mailchimp Standard plans enforce a 30-field audience limit and Premium allows 80. We inventory all Proton custom fields during scoping, consolidate overlapping fields, and map each to a named Mailchimp merge field. Any Proton custom field exceeding 255 characters is truncated with a note in the migration report. Checkbox fields from Proton map to Mailchimp radio or text merge fields depending on the customer's segmentation preference.

Proton Mail Labels (including color-coded tags) attached to contacts map to Mailchimp Tags. Each label name becomes a tag string on the audience member record. Tags in Mailchimp are used for segmentation and do not have the same hierarchical structure as Proton's nested labels, so we flatten the label path (e.g., Industry/Tech/Startup becomes three separate tags or a single combined tag depending on customer preference during scoping).

Proton label hierarchies that represent business categories (e.g., Lead Source/Prospect/Trade Show, Customer Type/Enterprise/EMEA) can be reconstructed in Mailchimp as Segments using multiple tag conditions. We document the label-to-segment mapping logic so the customer's marketing team can rebuild segments in Mailchimp's segment builder. Segments are not created during migration but the mapping specification is included in the deliverables.

Proton custom domains verified for inbound email routing map to Mailchimp authenticated domains for outbound deliverability. The DNS TXT records for DKIM (dkim._domainkey) and SPF must be added at the DNS registrar before Mailchimp can authenticate sends from the domain. We provide a domain verification checklist with the exact DNS record values required. Mailchimp's default sending domain (from its own infrastructure) is available immediately; custom domain authentication requires 24-72 hours for DNS propagation and DKIM validation.

Proton email addresses used for sending (as opposed to contact identity) map to Mailchimp's verified From email addresses. The From name, email address, and reply-to address are configured per Mailchimp audience. Proton's catch-all address configuration does not have a direct Mailchimp equivalent; we document the From address strategy during scoping to ensure the sending identity aligns with the audience's unsubscribe and reply handling.

Proton Mail hide-my-email aliases (up to 10 on Mail Plus, unlimited on Unlimited and higher) are extracted as separate address records. These are not imported as Mailchimp subscribers unless the customer specifically requests it, because aliases are typically throwaway addresses used for service signups rather than subscriber identity. We include alias data in the migration inventory with a recommendation to exclude from audience import unless the customer confirms the alias is a valid subscriber address.

If Proton has any records marked as unsubscribed, blocked, or bounced (tracked via Proton's own contact flags), we import these as Mailchimp suppressed contacts. Mailchimp requires suppressed records to be uploaded as a non-subscribed import so they are excluded from future campaigns. This step prevents accidentally emailing addresses that previously unsubscribed or bounced at the Proton level.