Need more detailed information about email bounces

[Anonymous]

The following help articles provide some insight into email bounces, but I can't find any detailed info about the questions below and hope someone can answer these.

• Soft and Hard Bounces in Email
• Email Invalid Cause Codes
• How Marketo Tracks Email Activity

1. Are all the SMTP error codes that start with "4" categorized as a soft bounce?
2. Which of the SMTP error codes that start with "5" are categorized as a hard bounce vs. a soft bounce?
3. Does the Sales Email Bounced event include both hard and soft bounces?
4. Not all hard bounces result in the Email Invalid field being set to "True" - which SMTP error codes cause this to occur?
5. Sometimes there is an Email Bounced Soft event (see details below) that occurs in the Activity Log at the same time as the Email Delivered event or several hours later ?  Is this because the delivery confirmation SMTP message is sent at a point prior to the point at which the bounce SMTP message is sent and if so, does this mean that the recipient likely did not receive the email? Below are the details for the Bounce events.

• NO MATCH DETECTED
• smtp;400 4.4.7 Message delayed
• smtp; 5.3.0 - Other mail system problem 554-'5.1.0 Sender denied' (delivery attempts: 0)    
• 550 [internal] [oob] The response text could not be identified.

[Anonymous]

Hello Elliott!

1.  Yes.  Category 1 (Email Suspended) and Category 2 (Email Invalid) are counted in the mail statistics as hard bounces, all other category numbers are soft bounces.

2.  Category 5 are also categorized as soft bounces.

3.  Sales Email bounces are categorized and handled just like regular Marketo mail bounces.

4.  Yes, category 2 sets "Email Invalid - true".

5.  The first is termed a "composite bounce", that is when a mail is accepted and then rejected during the same SMTP session.  In this case, that does mean that the mail recipient most likely did not get the mail delivered to their inbox.  If a mail is bounced much later, that means that it was accepted during the initial SMTP session, but then was rejected when the recipient server, for whatever reason, is unable to complete delivery to the inbox for the intended recipient.  This usually is an email that MTA sends back to us, which allows us to record the bounce.

[Jep_Castelein2]

Also see some background info in this document: Analyzing Email Deliverability (link fixed again)

[Anonymous]

Thanks Tony, can you provide the mapping of SMTP codes that correspond to Category 1 and Category 2.

Jep, the link you provided goes to Box and requires a login.

[Jep_Castelein2]

Elliott, I think the link should be fixed now. I put it on my public Dropbox folder. 

[Anonymous]

Hi Elliott,

This KB article has a partial interpretation of SMTP codes:
https://community.marketo.com/MarketoArticle?id=kA050000000KytY

[Anonymous]

Tony, I did note this help article in my initial post.  In fact, the title of this help article is a bit misleading as not all of these result in the Email Invalid field value being set to "True".  My question still remains as to which specific SMTP error codes are considered Category 1 and which are considered Category 2.

[Anonymous]

Thanks for this article Jep!  It is very helpful, but I still have a few questions.

1. The deliverability article indicates that Marketo will suspend sending emails for 24 hours to an email address that has a hard bounce due to anti-spam, but there is no mention of this for soft bounces.  The Soft and Hard Bounces in Email help article indicates that the Email Suspended field value is "set to True when a soft bounce occurs" - please confirm that this is correct.
2. How would we see a list of email addresses that had a sales email soft-bounce since there is only a single Sales Email Bounced filter?  
3. How would we see a (reasonably accurate) list of email addresses that had repetitive sales email bounces since there is not a Not was Delivered Email filter?
4. The example of handling repetitive bounces sets the Marketing Suspended field value to "True" - is there a condidtion that should cause us to change this value back to "False"?
5. The example Email Invalid Cause messages for "email invalid" bounces appear to be SMTP error codes 5.1.1 and 5.2.0 as well as the non-SMTP code message "BOUNCE FILTERS MATCHED MESSAGE BODY".  Are these the Category 2 (Email Invalid) responses that Tony referred to?  When I use the filters the article suggested to see a list of "Invalid Email" Bounces, the following Email Invalid Causes are found - are these also Category 2 responses?  Are you filtering responses for specific phrases as well as codes when determining if a bounce is Category 2 - if so, what are they? 

• INVALID EMAILID FORMAT - Missing '@' for TO recipient
• [SUPPRESS ACTION]
• [DNS ERROR] Non-existent domain, MX record
• 550 [internal] [oob] The recipient is invalid.
• smtp; 5.1.0 - Unknown address error 550-"xxx_x'xxx@xxx.com... No such user" (delivery attempts: 0)
• smtp; 550 No such user (xxx@xxx.com)
• smtp; 550 5.7.1 Unknown recipient <xxx@xxx.com> was submitted by host <serv01.obg.int.local>. Sender address was <mail001@trust-iadsm5-153.mktomail.com>.
• [VALID DOMAIN,1363972974,1,1] Exceeded MaxAttempts - 550 5.0.0 <xxx.xxx@xxx.com>... User unknown
• X-Mail-System; unknown user: "eshamshian"
• [Message Expired] Exceeded MaxAttempts - 450 4.7.1 <bonny@gifttree.com>: Recipient address rejected: Service is unavailable
• 550 5.4.1 xxx.xxx@xx.xxx.com: Recipient address rejected: Access Denied
• 550 Invalid Recipient

6. The example Email Suspended Cause messages for "Blocks" appear to be SMTP error codes 5.7.1, 5.5.3, 5.5.4 as well as the non-SMTP code message "BOUNCE FILTERS MATCHED MESSAGE BODY".  Many of these codes / messages were also Email Invalid Cause messages.  What causes Marketo to treat the same response differently (e.g. Email Invalid vs. Email Suspended)?
 

[Jep_Castelein2]

1. This is not correct. Email suspended is not set to True for soft bounces. I have notified the docs team. 

You may want to open a support ticket to request a call with our deliverability team, the have the deepest knowledge in this area. 

Best, 
Jep

[Anonymous]

Thanks Jep!  I opened a support case as you suggested.

You should also have your docs team look at the How Marketo Tracks Email Activity help article as it has several errors/omissions.

• It indicates that all hard bounces have their "Email Invalid field set to true"
• It has "Email blocked" as a separate sub-head from the "Email bounces" (Soft bounce / Hard bounce) subhead, which is a bit confusing since a blocked email is a type of hard bounce. 
• It doesn't mention the "Technical Issue" hard bounces that have neither their Email Invalid or Email Suspended fields set to true.