Keeps your mailboxes and domains healthy, so your emails keep reaching the inbox.
Skips addresses known to bounce, for any mailzy customer. Bounces hurt every mailbox the campaign uses.
Catch-all, role and unknown addresses (as the Email Verifier calls them) are skipped unless this is on.
Some companies pass incoming mail through a security service such as Proofpoint or Mimecast, which is strict with cold email - emails to them rarely arrive. While this is off, nobody behind one is emailed. A few services can't be seen from outside, so some may not be detected. Changing it brings back the leads it skipped - resume the campaign if it has finished.
Adds the header Gmail, Yahoo and Outlook use for their own Unsubscribe button. It protects your sender reputation.
Gmail addresses hear from your Google mailboxes and Outlook addresses from your Microsoft ones, when the campaign has both.
Provider routing
Rules for which of your mailboxes may email which providers - for example, never from Google mailboxes to Microsoft addresses.
Off for your workspace - turn it on in workspace guardrails, or give this campaign its own limit below.
Company spacing is off for your workspace. The company limit, spacing and bounce pause are set once, for every campaign.