Moving a newsletter without losing readers

Moving a newsletter to another platform is not a file transfer. The list copies over in minutes; the thing that breaks is deliverability, because the new sender has no history with the mail providers that decide whether your mail reaches an inbox or a spam folder.

Export everything, not just the addresses

Take the full export, not the address column. Subscription date, the source of each sign-up, the confirmation record, unsubscribes and bounces, and whatever engagement history the platform keeps. The dates and consent records are what let you prove a list is legitimate if the new provider asks, and providers do ask.

Export the suppression list as well — the people who unsubscribed or complained. Losing it is the classic migration failure: those addresses come back into the fresh import, receive mail they opted out of, and complain again, which is the fastest way to a poor sender reputation on day one.

Use the export to clean up while you are there. Addresses that have not opened anything in a year are the ones most likely to bounce or sit in spam traps, and they cost you reputation at exactly the moment you have none to spare.

Authenticate before you send

Set up SPF, DKIM and DMARC for the sending domain on the new platform, and confirm they pass on a test message before any real send. Mail from a domain that authenticates correctly is treated as a known quantity; mail that fails is treated as suspect regardless of what it contains.

Keep the same sending domain if you can. The domain carries much of the reputation, so a move between platforms with the domain unchanged is far gentler than a move to a new one.

Warm up, then announce

Do not send to the whole list on the first day. Start with the most engaged few hundred readers, then widen in steps over a week or two, watching bounces and complaints at each stage. Engaged readers open and reply, and that early signal is what teaches mail providers the new sender is wanted.

Tell readers before the switch, in the last issues from the old platform: the new sender address, what will change, and a request to add the address to their contacts. Keep the old account open, read-only, for a month or two afterwards, so nothing depends on a service you have already stopped paying for.