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.

[Elliott_Lowe1]

Below are  the help articles mentioned in this thread with updated links in the new Community and Product Docs areas.

How Marketo Tracks Email Activity

Email Bounce Codes

Soft and Hard Bounces in Email

Also, there is a new blog post by Ed Masson​,Making sense of Marketo email bounce categories, which expands on Ed's comment in this discussion.

Jep Castelein, is the  Analyzing Email Deliverability ​ document you provided in this discussion current?

Also, I discovered that Marketo does not send emails to leads whose email addresses have an invalid format or characters instead it logs an Email Bounced Soft activity record whose Detail field is 'System send failure: To address parse error...' or 'System send failure: Email injection error'.  These really should haveth eir Email Invalid field value set to 'true',so that they are not included in the email statistics.  Please vote for the   Idea if you agree.

[Jep_Castelein2]

Elliott Lowe​ the document has not updated in the last 2 years, so some things may not be up to date. The main concepts should still apply, but there could be some changes with Smart List details because Marketo changed to a new email engine (from Strongmail to Message Systems) since I wrote the document.

[Anonymous]

If there is a doc that you think we should update, let me know : )
Just make sure to @mention me so I see your note..

Scott

[Delinda_Tinkey1]

Is there documentation on what bounce codes trigger Marketo to flag the email address as invalid? Does Marketo ever un-flag the email invalid status?

[Elliott_Lowe1]

Ed Masson noted in his reply above that a Category 2 Hard Bounce results in the Email Invalid field value being set to 'true'.  He also has that in his recent Making sense of Marketo email bounce categories blog post.  Also, in the replies to the Monitoring Email Deliverability: Bounces - Part I Marketo Whisper Implementation tips, the Marketo author acknowledged that this was the case. I've submitted a suggestion in the https://docs.marketo.com/display/public/DOCS/Hard+and+Soft+Bounces+in+Email Product Doc that they should add this along with the detailed info about email bounce categories.  Please also submit a suggestion for this in the Product Doc and hopefully Marketo will formally document this.

[Anonymous]

I've spent a lot of time working through email deliverability issues with different ESPs and platforms over the years. I do have some issues with the current way Marketo handles some of their hard bounces. To me a Hard Bounce is ONLY true if user is unknown or permanently blocking email from ALL recipients.

To answer your question about categorizing a 4 as soft vs 5 being hard, I've found they are all slightly different based on ISP.

For example,

AOL renders the following bounce codes:

source: AOL Postmaster - Error Codes

• 554 - Typically Spam, I would categorize as a Soft Bounce, but Marketo will render these hard bounces. Spam complaints generally are time constrained and can be removed after X hours.
• 421 - Usually related to issues with rDNS records, SPF records, or other issues with the IP and domain relationship. HOWEVER, there are some 421 errors related to spam that appear, which makes this bounce code a bit confusing. Marketo most likely would render these bounce codes as SOFT. (Correct me if I am wrong here). 421 DYN: T1 is one I've had problems with in the past that is related to influx of spam complaints on a new IP.
• 521 & 550 - Dead email or user blocking email. These are what I would consider true HARD bounces and should never be mailed again. 

Again each ISP is different in the way they render bounces.

The problem I have with the current setup is that its not fail proof. If Marketo wants to categorize SPAM related issues (on the ISP) as a HARD bounce then the following should not show up as a SOFT Bounce.

550 5.7.1 <xxxxxxx>... Denied by Grande Block List - see https://secure.mygrande.com/postmaster/gbl/

I have to dig through my activity log and monitor these bounces quite frequently since we are in the process of warming up a new IP.

What is the solution?

To me each error code needs to be manually reviewed on a frequent based to make sure they get labeled properly. If Marketo wants to consider spam issues a HARD bounce, the Big 5 (AOL, Hotmail, MSN, Yahoo, Gmail) + The Cable ISPs (Verizon, ATT, Grande, Comcast, & Many More!) need to be monitored to make sure the code gets labeled correctly.

Hope this Helps!

[Delinda_Tinkey1]

This is great information! I hope Marketo finds this thread and updates the documentation. Many people could benefit.

[Anonymous]

Delinda Tinkey​

We are on it

- Scott : )

[Dory_Viscoglio]

Wow!  There's a lot to digest here, but it's so much more valuable than the standard community article that talks about soft and hard bounces.  Thanks for all of the work that everyone has put into these responses, they were invaluable in helping me make recommendations regarding our email policy amongst the 3 systems that we're currently using.

[Edward_Masson]

I worked with support some time ago and got some tips on Email Bounce Category.
 
The Marketo Mail servers use "Strongmail" as the mailing software and Strongmail stamps email with 1 of 6 different bounce categories. You can create Smart Lists for each of the 6 categories (1,2,3,4,7,9) set them to look at the last 7 days and show the leads.
 

• Category 1 – Should be Email Suspended (usually from spamblock). You may find leads (particularly Gmail addresses) that are Category 1 bounces, but have no data in Email Suspended or Email Suspended at. They are STILL problematic leads. You could also add a further constraint for the # of times they hit Category 1.

• Category 2 – Email Invalid. Anyone who has a Category 2 bounce should be email invalid. Leads in this category should be considered for being marked email invalid if they are not already.

• Category 3 – Soft Bounce. “Mailbox is full”, that kind of thing. Temporary. Repeat offenders may be an issue.

• Category 4 – Technical. Something was wrong with the mailserver on the other end. Again, temporary, but you might want to look for minimum # of times.

• Category 7 – Proprietary, used for Strongmail internally.

• Category 9 – Unknown. Nonsensical errors, non English, etc.

[Michelle_Tizian]

Elliott,

Are you lone person who does everything you mentioned above in terms of tracking spam blocks and invalids? What about tracking spam complaints?  How often do you do list hygiene? Is it weekly, monthly or daily?

I created a web page on our site for white listing instructions because some people find it easier to send a short email with the whitelist instruction link on it. Just like you we send from our company email server.  But there are some instances where even that is being blocked. So I have someone else in the company reach out to them. 

Are you doing any certification?  I was thinking of doing the one from Returnpath.

[Anonymous]

We have done batch submits of our email addresses to StrikeIron to validate the Invalid Email status, which helps keeps these to a minimum, but I hope to implement a real-time validity check with StrikeIron when someone submits a form.

Of course people still leave their company, etc., so we periodically if we have lead records that  have the Email Invalid field set to true and that lead has had no activity in the last 6 months, we change the revenue stage from "Inactive" to "Bogus Info".

If we get repeated hard bounces due to spam blocks (e.g. Email Suspended for 24 hours), I check to see if the IP address for our shared Marketo email server is blacklisted (it rarely is).  If it's a customer, we have our customer success rep contact them by Outlook email (sometimes these go through when Marketo sent emails don't) or by phone and we ask them to white list our email address / domain and email server IP, so that they will get our emails.

[Anonymous]

Hi Elliot,

RE: I check to see if the IP address for our shared Marketo email server is blacklisted (it rarely is).

How would I validate if my IP address is blacklisted or not?

Thank you in advance, Lana

[Michelle_Tizian]

Thanks for posting this information Elliott.  I  struggle with the bounces all the time. So what do you guys do on your end when you get the different categories of bounces? 

[Anonymous]

Elliott, I have your support ticket now, I'll be writing you back shortly!

[Kimi_Heskett1]

Lots of good info in this thead, thanks all!

[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.

[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 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)?
 

[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.