# Mail delivery subsystem detection

**URL:** <https://community.hubspot.com/t/mail-delivery-subsystem-detection/30995>\
**Category:** Sales Email\
**Tags:** starter\
**Created:** [January 29, 2021, 3:59pm UTC](https://community.hubspot.com/t/mail-delivery-subsystem-detection/30995 "2021-01-29T15:59:28Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![ElisaAlvarez](https://d10pqhm3lwygmk.cloudfront.net/user_avatar/community.hubspot.com/elisaalvarez/32/79644_2.png) [@ElisaAlvarez](https://community.hubspot.com/u/ElisaAlvarez)\
**Post date:** [January 29, 2021, 3:59pm UTC](https://community.hubspot.com/t/mail-delivery-subsystem-detection/30995/1 "2021-01-29T15:59:28Z")

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Hi!

When enrolling multiple people on a sequence there’s a great number of contacts that are not going to be delivered the email, and I will receive an automated email that most of the times read “Adress not found” - Email Delivery Subsystem; or “Your message couldn’t be delivered” - Postmaster.

I would like to know if there’s a chance for me to identify them over HubSpot and not Gmail, so the sequence stops and I can update the information.

Also, is there a chance this same idea can be drafted over a workflow, so that any time I receive this kind of automated email, the sequence stops and it notifies me?

Thank you 🙂

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**Author:** ![karstenkoehler](https://d10pqhm3lwygmk.cloudfront.net/user_avatar/community.hubspot.com/karstenkoehler/32/68554_2.png) [@karstenkoehler](https://community.hubspot.com/u/karstenkoehler)\
**Post date:** [January 29, 2021, 4:10pm UTC](https://community.hubspot.com/t/mail-delivery-subsystem-detection/30995/2 "2021-01-29T16:10:58Z")

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Hi @ElisaAlvarez,

When a contact bounces in a sequence, they will automatically be unenrolled, see [here](https://knowledge.hubspot.com/sequences/unenroll-from-sequence). When you navigate to your sequence (Menu \> Automation \> Sequences) and click on it, you should see a list at the bottom of the screen where you can filter sequence activity by status, including “Errors”:

 ![37252iE141EA1ECCB566DC.png](https://d2qpr2jzcazej7.cloudfront.net/original/3X/b/c/bccd1271c3fa187b0791960eb354780892549ed0.png)

Technically you can re-build sequences in marketing workflows, yes. You’d have to create automated emails for each email of your sequence. Similar to sequences, you’d see bounces in the workflow _Performance_ tab. However, these workflows wouldn’t stop when a contact replies to an email – a key feature of sequences. (see [here](https://knowledge.hubspot.com/sequences/unenroll-from-sequence#automatic-unenrollment))

Also keep in mind that automated workflow emails would be sent using your connected email domain. Sequence emails are sent through your connected personal inbox.

Hope this helps!

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**Author:** ![ElisaAlvarez](https://d10pqhm3lwygmk.cloudfront.net/user_avatar/community.hubspot.com/elisaalvarez/32/79644_2.png) [@ElisaAlvarez](https://community.hubspot.com/u/ElisaAlvarez)\
**Post date:** [February 4, 2021, 8:42pm UTC](https://community.hubspot.com/t/mail-delivery-subsystem-detection/30995/3 "2021-02-04T20:42:37Z")

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Thank you,

I understand those bounces and how they reflect themselves as errors, however, the ones that I’m interested to know if I can join on a list or identify, are the ones that cannot be sent to the contact because they have been stopped. When I enroll multiple contacts on a sequences, it’s ver common that I receive emails that look like this:

![37504iD6C8570449C2BE0B.png](https://d2qpr2jzcazej7.cloudfront.net/original/3X/3/8/384d34c9bceecacda2d5197a0cfe671d198260e2.png)

I’d love to know how to get them together, for they are contacts that cannot be reached and that should be updated.

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<div class="post-metadata">

**Author:** ![karstenkoehler](https://d10pqhm3lwygmk.cloudfront.net/user_avatar/community.hubspot.com/karstenkoehler/32/68554_2.png) [@karstenkoehler](https://community.hubspot.com/u/karstenkoehler)\
**Post date:** [June 21, 2021, 4:26am UTC](https://community.hubspot.com/t/mail-delivery-subsystem-detection/30995/4 "2021-06-21T04:26:42Z")

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Hi @ElisaAlvarez,

My apologies for the looong delay here.

You should be able to get this list of contacts by creating an active contact list and filtering for contacts with “_Email hard bounce reason_ is known” and “_Now in sequence_ has ever been equal to true”.

Hope this helps!