Duplicates merged
Two records for the same person are merged by keeping the most recent value in each field, never by overwriting at random.
Email contact import and migration
Transvase pulls your contacts out of any file or tool, clears out the dead addresses, maps your fields for you, and loads them into your new platform. You review it, you approve it, it's done.
No credit card on the Starter plan · Nothing is imported until you approve it
Your files are deleted from our servers 72 hours after the import.
| Column in your file | Destination field | Status | |
|---|---|---|---|
| Email address | → | matched | |
| Full name | → | FIRSTNAME + LASTNAME | split |
| Mobile phone | → | SMS (E.164) | reformatted |
| Signup date | → | OPT_IN_DATE | matched |
| j.miller@gmial.com | → | gmail.com | corrected |
| 127 duplicate addresses | → | merged | cleaned |
| 309 addresses that don't exist | → | dropped | blocked |
Why imports go wrong
The file goes through, the platform says "imported", and the campaign goes out with 900 "Hi {FIRSTNAME}" greetings and a bounce rate that damages your sender reputation for months.
Past a 3% bounce rate, mailbox providers start sending your messages to spam — including the ones going to your best customers. A list from 2019 often has 10% of them.
"Mail", "e-mail", "Email address", "Contact mail". Three exports, three formats, and nobody on the team wants the job.
The same customer gets the promotion twice, under two different first names. That is the kind of detail that makes a loyal customer unsubscribe.
Transvase opens your file, checks it, and shows you the three numbers that matter — dead addresses, duplicates, missing fields — while there is still time to decide.
How it works
It fits in one sentence: we show you exactly what is about to be imported, row by row, before anything is touched.
Drag in a CSV, an Excel sheet or an Outlook export, or connect your old platform directly. Unusual separators, mangled accents and empty columns are handled for you.
Columns are recognized automatically, phone numbers put back into international format, common domain typos corrected, duplicates merged. You change anything you like in one click.
The contacts go over to your platform with their lists and their tags. A report names every address that was dropped, and why. For seven days, one undo puts everything back.
What Transvase does that your platform does not
Every address is checked against the receiving server. Closed mailboxes and spam traps are dropped before they reach your list, not after the campaign.
"E-Mail Addr", "e_mail_work", "Contact mail": the usual headers are recognized straight away, and your corrections are remembered for the next import.
Two records for the same person are merged by keeping the most recent value in each field, never by overwriting at random.
Proof of consent and its date travel with the contact all the way to the destination. Your consent records stay complete after the migration.
Connect a Google Sheet or a URL, and new contacts come in every night, through the same quality checks.
An import you are not happy with rolls back completely. The contacts it added are removed, the records it changed go back to how they were — no support ticket, nothing to ask us for.
Proof
"Our agency had quoted three days of work. Transvase did it in one afternoon — and it caught 2,100 dead addresses we would have mailed without knowing it."
CRM manager · medical equipment distributor, 38,000 contacts
Mailchimp → Brevo migration, March 2026
Pricing
You are never billed for contacts that verification drops.
Common questions
They are encrypted on arrival, kept on servers located in France, and deleted automatically 72 hours after the import ends. You can also delete them yourself at any time from the app. We never use your contacts for anything other than your import.
Nothing is imported until you approve it. The review screen shows the first five rows exactly as they will arrive at the destination, and every mapping can be changed from a drop-down. If you only notice afterwards, the seven-day undo puts the list back the way it was.
Any platform that accepts a CSV import or has an API works: Transvase produces a file in the exact format the destination expects, or sends the contacts straight over by webhook. Send us the name of the tool and we will confirm within 24 hours.
The date and the source of consent travel with each contact whenever your file has them. When they are missing, Transvase says so plainly rather than inventing a date — it is your call whether those contacts go into the list.
Reading and cleaning take about ten minutes. Verifying the addresses against the receiving servers, which is the slow step, runs around an hour and a half for 50,000 addresses. You get an email when the report is ready.
Free trial
Drop in a sample of your file: you get the full quality report before you even create a paid account.