What is a “vacation response” vs “temporary bounce”?
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You send a campaign, and two replies come back almost instantly. One says "Thanks for reaching out, I'm on vacation until the 14th." The other is a wall of server error text from MAILER-DAEMON. Both land in your bounce logs. Only one of them actually means something went wrong.
A vacation response (also called an out-of-office reply) is an auto-reply that fires from a delivered mailbox. Your email got there. It was received. The subscriber just set up an automatic message to let people know they're away. That's a healthy, active, human-managed inbox. You don't need to do anything with it.
A temporary bounce is a completely different animal. Your email never arrived. The receiving mail server sent back a failure notification, usually with a 4xx error code, because something got in the way. Common culprits include an over-quota mailbox, a temporarily suspended account, or a brief server outage. Your ESP will typically retry delivery for a day or two before giving up.
Here's where it matters for your list. If your bounce processor misreads a vacation response as a bounce, you might suppress a perfectly good subscriber. That's a real cost. The opposite mistake (treating a bounce as harmless chatter) isn't as bad, but if a soft bounce keeps happening for the same address, it's worth watching. Several soft bounces in a row often signal a mailbox that's heading toward being deactivated entirely.
The easy way to tell them apart: vacation responses come from the subscriber's actual address and arrive as normal email messages. Bounces come from MAILER-DAEMON or a postmaster address and contain server error codes, not personal messages. Good ESPs handle this distinction automatically, but it's useful to know what you're looking at when something slips through.
If your bounce handling feels messy or you're not sure how your platform is classifying these, it might be time to give your list a proper clean. We do that, and we'll catch the ones that are quietly heading toward a hard bounce before they hurt your sender reputation ;)
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