On the Email Users page, select the mailboxes (up to 100), then click Replace Usernames in the selection bar. Enter a new username for each mailbox, or type a first and last name and click Generate to fill them all with variants like first.last. Confirm by typing REPLACE. Each mailbox is deleted and recreated on the same domain with the new address and a fresh password — all messages in the old mailboxes are permanently lost, so export the new credentials and reconnect your sending tools afterwards.
When to use this
Replace Usernames exists for one job: you want to keep your domains (and their reputation) but the addresses on them are wrong — a persona you no longer use, a client engagement that ended, or naming that doesn't fit the new campaign. Instead of deleting mailboxes and recreating them by hand, one flow does both, per mailbox, in order.
Typical cases:
- Repurposing infrastructure after a client or campaign ends — 60 mailboxes named after someone you no longer send for.
- Changing personas on pre-warmed mailboxes — pre-warmed addresses come with sample names; replace them with your own while keeping the aged domain.
- Fixing a naming convention — moving everything from
jsmith@style tojohn.smith@.
If you only want to change the display name (what recipients see in the From field), don't use this — that's a safe, instant edit. See Rename or edit a mailbox.
What it costs you (read before confirming)
Replacing is deliberately loud in the app because it's destructive:
- Every message in the old mailboxes is permanently deleted. There is no undo and no recovery.
- New passwords are generated. Every sending tool connected to the old addresses stops working until you export the new credentials and reconnect.
- Warming restarts. Mailboxes that had warming on get it re-enabled automatically on the new address, but they start warming from day one again. Plan sending volume accordingly.
What you keep: the domains, their DNS setup, their reputation, and your mailbox count and billing — a replacement is one-for-one on the same domain.
Pre-warmed mailboxes
Pre-warmed mailboxes normally can't be deleted individually — they're managed as a set with their domain. Replace Usernames is the supported way to change their addresses. The domain's age and reputation stay with you (that's most of what you paid for); the per-mailbox warmup history stays with the old address and doesn't carry over. Your pre-warmed billing is unchanged.
While it runs
After you confirm, the progress screen shows each domain as it completes. You can close the window — the work continues in the background, and larger batches take a few minutes. New mailboxes appear in the Email Users list as they're created.
What's next
Step-by-step
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1. Select the mailboxes
On the Email Users page, tick the checkboxes for the mailboxes you want to change (shift-click selects a range). Up to 100 at a time.
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2. Open Replace Usernames
Click Replace Usernames in the selection bar that appears above the table.
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3. Enter the new usernames
Each selected mailbox gets a row grouped under its domain. Type a new username per row, or enter a first and last name at the top and click Generate to fill every row with variants (first.last, f.last, last.first, and so on) — you can still edit any row.
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4. Confirm
Read the warning, type REPLACE, and confirm. The old mailboxes and every message in them are permanently deleted — there is no undo.
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5. Reconnect your tools
When the progress screen shows each domain completed, export the new credentials and update your sending tool — the old addresses and passwords no longer work.
Frequently asked questions
Why does replacing a username delete the mailbox?
The username is the mailbox's identity — it's baked into login credentials and how providers see the sender. Mail servers can't rename a mailbox in place, so Winnr deletes the old one and creates a new one on the same domain in a single guided flow.
Are the messages in the old mailbox kept?
No. Everything stored in the old mailbox is permanently deleted and cannot be recovered. If you need anything from those inboxes, save it before replacing.
Do the new mailboxes keep the old passwords?
No — each new mailbox gets a fresh password. Export the new credentials afterwards and update any sequencer or tool that connects to those mailboxes.
What happens to warming?
Warming restarts from scratch on the new addresses. If a mailbox had warming enabled, Winnr re-enables it automatically with the same settings — but the warmup history belongs to the old address and doesn't carry over.
Does this work for pre-warmed mailboxes?
Yes — this is the one way to change pre-warmed addresses (they can't be deleted individually). Your domain keeps its built-up reputation and your billing doesn't change, but the individual mailbox warmup history doesn't transfer to the new address.
Does it change my mailbox count or billing?
No. Each replacement is one-for-one on the same domain, so your mailbox usage, limits, and billing are unchanged.
Can I do this via the API?
Yes — POST /v1/email-users/replace with the mailbox IDs and new usernames. It returns a job you can poll. Full schema at [app.winnr.app/docs](https://app.winnr.app/docs).