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How to fix soft bounces

What is a Soft Bounce?

A Soft Bounce means there was a temporary problem with the receiving server accepting the email. We make several attempts to send a message if we get an error when attempting delivery. When a message status shows as Soft Bounce or Undeliverable, it means we have ceased attempting to send that message.

If you expand the bounce information using the More Details button, you can see some additional information about the attempts Postmark made to deliver the message.

For example:


Delivery attempt history for your mail:
Wed, 04 May 2016 01:53:12 +0000 (GMT)
TCP active open: Failed connect() to TCP port 25 of 88.79.130.53(No formatted text for errno = 113)TCP active open: Failed connect() to TCP port 25 of 88.79.130.53(No formatted text for errno = 113)
Tue, 03 May 2016 05:20:51 +0000 (GMT)
TCP active open: Failed connect() to TCP port 25 of 88.79.130.53(No formatted text for errno = 113)TCP active open: Failed connect() to TCP port 25 of 88.79.130.53(No formatted text for errno = 113)
Mon, 02 May 2016 21:20:45 +0000 (GMT)
TCP active open: Failed connect() to TCP port 25 of 88.79.130.53(No formatted text for errno = 113)TCP active open: Failed connect() to TCP port 25 of 88.79.130.53(No formatted text for errno = 113)
Original-recipient: rfc822;softbounce@domain.com
Final-recipient: rfc822;softbounce@domain.com
Action: failed

Status: 4.4.7 (unable to deliver this message after 4 days)


How do I fix it?

Soft bounces need to be resolved on the receiving mail server side.

You can wait a day or two before attempting sending to this recipient again to see if the issue has been resolved. If the issue persists for more than 48 hours, you may want to contact the recipient through another channel, provide them with the bounce details, and let them know to have their mail administrator or IT team take action to correct the problem.

If the recipient gets in touch with you wondering why they haven't received your email, direct them to contact their IT team or mail administrators to resolve the problem with their mail server.

Once the problem is resolved on the receiving mail server side, you can immediately send to them again and resend any failed messages. You do not need to reactivate Soft Bounce addresses before sending to them again.

Last updated October 30th, 2018

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