Do I keep my sender reputation?

Mostly, if you keep the same sending domain. Reputation sits with the domain, not the tool, so reuse the subdomain you sent from before and add day3's DKIM records to it.

Will unsubscribed people be mailed again?

Not if they come across marked. Include a status column in the CSV and rows marked unsubscribed import as unsubscribed. Rows marked bounced or spam are skipped, which is why the suppression list goes in first.

My list is bigger than 5,000 rows. What now?

Split the export into files of 5,000 rows and import them one after another into the same audience. Re-importing an address doesn't create a duplicate.

Can I do all of this over the API?

The list, yes: audiences, contacts and suppressions all have endpoints, and the docs have a step-by-step guide for moving a list that way. The sending domain is set up once, in the app.

Does the test send cost anything?

It counts against your monthly allowance like any email, since it's a real send. With five recipients at most, that's five emails.

Migrate

Moving to day3, screen by screen.

Five steps: your domain, its DNS records, your list, and a test email. Every picture below is the real app.

1

Add your sending domain

Under Sending, add the domain you send from, plus the From name and address. If you're moving from another platform, reuse the subdomain you sent from there: inboxes remember how a subdomain has behaved, and a new one starts from zero.

The Add a sending domain dialog in day3, with fields for domain, From name and From email, and a note on reusing the subdomain from your old platform.

2

Copy the DKIM records to your DNS

day3 shows each record as a card with its type, name and value, each with a copy button. Paste them in wherever your DNS lives. There's nothing to submit: day3 checks for the records itself and marks each one Found.

The DNS records step for a domain in day3, listing DKIM CNAME records with copy buttons and a Found badge on each.

3

Add SPF and DMARC

The third step adds a custom Return-Path (an MX record and an SPF TXT record) and a DMARC record. Your domain sends without them, but they help more of your mail land in the inbox, so add them while you're in your DNS anyway.

The Extra inbox protection step in day3, showing the Return-Path MX record and the SPF TXT record, both found.

4

Load your suppressions, then import the CSV

Export your list from the old tool. Put its bounces and spam complaints on Suppressions first, so they stay blocked. Then open an audience and import the CSV: it needs an email column, first_name and last_name are optional, and any other column becomes a custom field. A status column carries unsubscribes over as unsubscribed. Up to 5,000 rows per file.

An audience in day3 with the Import CSV button and the note on carrying opt-outs over from another platform. The subscriber list is hidden.

5

Send yourself a test

Open a campaign and press Send test. It goes to up to five addresses you name, with [Test] in the subject line, through the same pipeline as a real send. Check it lands in the inbox, from your domain, before you send to anyone else.

The Send a test email dialog in day3, with one recipient address filled in and a Send test button.

Moving by API instead?

The list part of the move works as API calls: create the audience, load suppressions, import contacts. The docs guide has the order and the requests.

Read the API migration guide

Questions

Do I keep my sender reputation?: Mostly, if you keep the same sending domain. Reputation sits with the domain, not the tool, so reuse the subdomain you sent from before and add day3's DKIM records to it.
Will unsubscribed people be mailed again?: Not if they come across marked. Include a status column in the CSV and rows marked unsubscribed import as unsubscribed. Rows marked bounced or spam are skipped, which is why the suppression list goes in first.
My list is bigger than 5,000 rows. What now?: Split the export into files of 5,000 rows and import them one after another into the same audience. Re-importing an address doesn't create a duplicate.
Can I do all of this over the API?: The list, yes: audiences, contacts and suppressions all have endpoints, and the docs have a step-by-step guide for moving a list that way. The sending domain is set up once, in the app.
Does the test send cost anything?: It counts against your monthly allowance like any email, since it's a real send. With five recipients at most, that's five emails.