Email Bounced Soft Details

[Anonymous]

Hi All, 
Does anyone know what it means when an email soft bounces with an error that says "550 [internal] [oob] The response text could not be identified"?

Thanks!

[Anonymous]

Megan,

The actual text  can vary on these messages and is customizable. How ever in this case the domain used in the email address could be bad and not recognizable ....make sure the email address if normal, has no additional characters saved along with it or correct any typos.

[Anonymous]

Here are two websites which show the basic codes. They are as Don said completely customizable by the admin of the company's firewall. So they can be changed on will. It makes it quite hard for marketeers to automate reactions if they change, but here are what are considered the industry standards.

Resource List 1
Resource List 2

[Anonymous]

I have been struggling quite a bit on how to manage bounced emails in Marketo and would really appreciate some guidance.

Recently we have seen considerably high percentage of soft bounces approximately 10% of our total email sends.After investigating deeper into Marketo soft bounces we saw that Marketo is marking emails with smtp response code of 550 as soft bounces.

But from reading online discussions smtp 550 response code is mostly and always an invalid or unavailable mailbox (http://www.gettingemaildelivered.com/what-those-smtp-error-codes-mean-and-why-you-should-care), so shouldn't Marketo be marking them as Hard bounces instead of soft bounces. Please help clarify. Even Don's comment above suggests that 550 would propably be hard bounce.