Reconnecting a Mailbox Without Losing Campaign Progress
TL;DR: If you just want to change a setting (like the daily sending limit), DO NOT disconnect and reconnect. Use the Edit Daily Limit option on the Mailboxes page — it is live and non-disruptive. Only delete-and-reconnect when the mailbox is genuinely broken (expired credentials, provider migration, persistent auth errors). Deleting creates a NEW mailbox record with a new internal ID, which requires a small manual follow-up step to keep campaigns flowing.
What Survives a Delete
Prospects are NEVER deleted when you remove a mailbox. Specifically:
• Prospect rows remain in the database with their full sequence history.
• The sequence step cursor (which email they are on) is preserved — leads will NOT restart at Email 1.
• Reply-thread message IDs (`lastSentMessageId`) are preserved, so threaded replies continue to stitch correctly.
• Campaign enrollments, suppression entries, opens, clicks, and replies all remain intact.
What Happens Technically
When you delete a mailbox, the system runs a safe cleanup: every in-flight prospect that was assigned to that mailbox has its `mailbox_id` nulled (set to NULL, not deleted). The prospect stays in the campaign, waiting for the scheduler to pick a new mailbox from the campaign's pool on the next tick. The next scheduled send is pushed out by an hour so nothing fires immediately.
REQUIRED Action After You Reconnect
This is the step people forget: after reconnecting, manually add the newly-connected mailbox to each affected campaign's mailbox pool.
• Go to Campaign → Settings → Mailboxes.
• Toggle the new mailbox on (or add it if it is not listed).
• Save.
Without this step, the affected prospects have no mailbox to send from. The scheduler will keep rescheduling them +1 hour indefinitely, and your campaign will appear 'running' but produce zero sends until a valid mailbox is available.
Thread Continuity Is Safe
Replies to Email 1 and Email 2 continue to thread correctly even after a reconnect. Thread IDs are stored on the prospect row (`lastSentMessageId`), not on the mailbox, so a new mailbox ID does not break References/In-Reply-To stitching.
Daily Limit Changes — Do Not Disconnect
If your only goal is to change the daily sending limit, use the 'Edit Daily Limit' option on the Mailboxes page instead. It is live, requires no reconnect, and preserves the mailbox's internal ID — meaning every campaign keeps sending without any manual pool update. See the 'Editing a Mailbox's Daily Sending Limit' guide above.
Warmup-Enabled Mailboxes
Warmup stats (health score, inbox rate, spam rate, 7-day rolling history) are tied to the mailbox record. When you delete and reconnect, those stats reset because it is technically a new record. Plan for a short re-warmup period (a few days to a week) before running heavy campaign volume on the reconnected mailbox — this is another reason to avoid unnecessary reconnects.