How PostaSend Handles Email Deliverability So You Don't Have To

When you call client.emails.send(), PostaSend does more than forward your email to a mail server. It runs a series of checks and processes in the background that protect your sender reputation, keep your list clean, and ensure your next email has the best possible chance of reaching the inbox. Understanding what happens behind the scenes helps you build a more reliable email integration and debug problems faster when they do occur.

Bounce handling is the first layer. When an email bounces, PostaSend classifies it as either a hard bounce (permanent failure, the address does not exist) or a soft bounce (temporary failure, the mailbox is full, the server was unavailable). Hard bounces are added to your account's suppression list immediately and automatically. Attempting to send to a hard-bounced address again is one of the fastest ways to damage your sender reputation, because it tells inbox providers that you are not maintaining a clean list. PostaSend stops that from happening without you writing a single line of list-management code.

Complaint processing works the same way. When a recipient marks your email as spam using the 'Report junk' button in Gmail or Outlook, the mailbox provider sends a complaint notification back to PostaSend via a feedback loop. PostaSend processes the complaint, suppresses the address, and fires a webhook event to your endpoint so you can update your own database. A complaint rate above 0.1% is the threshold where inbox providers start treating all of your mail with more suspicion, staying well below that threshold is critical, and automatic complaint suppression is the most reliable way to do it.

Underneath all of this is IP reputation management. PostaSend monitors sending reputation signals continuously, Gmail Postmaster Tools data, Microsoft SNDS signals, and third-party blacklist feeds. If an issue is detected, the routing layer adjusts automatically, shifting traffic to IPs with cleaner reputations before you even notice a problem. You do not need to manage IP warming schedules, monitor blacklist feeds, or rotate credentials when a reputation issue is detected. The infrastructure handles it, and you get the full picture in your deliverability dashboard.