Deliverability
What are sender bounces?
A sender bounce means the sending mailbox was rejected — quota exceeded, mailbox disabled, authentication failed — not that the recipient was invalid. Fix the sender before you resume volume.
Recipient bounce vs sender bounce
- Recipient bounce — their side refused the address (disabled, full, does not exist). Clean the list.
- Sender bounce — *your* mailbox was not allowed to send. The recipient never had a chance.
Sender bounces show up as 5.7.x policy errors, quota exceeded, authentication failures, or "sender rejected" in a sequencer.
Common EmailPal-related causes
- Hit the daily cap and the remote said quota
- Mailbox deleted or password rotated and the sequencer still has the old SMTP secret
- Warming or sending held after a warmup bounce
- DNS no longer valid, so the receiving server treats you as unauthenticated
What to do
- Export fresh credentials. Export mailbox credentials.
- Confirm the mailbox still exists.
- Confirm DNS. DKIM not validating.
- Resume only after a test to a seed you control.
FAQs
Does EmailPal auto-replace burning mailboxes?
Pre-warmed inventory is claimed as a set; we do not silently swap addresses under you. If a hosted mailbox is dead, delete it and provision another, or claim a new pre-warmed domain.