Unusual bounce increase

[Emilia_Chioncel]

Hi Community,

Wonder if any of you encounter a higher bounce (both hard and soft) this month, such as double (5-6%) than in the previous months (2-3%)?

A couple of the bounce details for records that were not bounced in the past:

550 Unable to add --- because host ---- is listed on bl.spamcop.net

550 JunkMail rejected - ---.mktomail.com [---- is in an 550 RBL: Blocked - see http://www.spamcop.net/bl.shtml?---

550 spamcop.mimecast.org Blocked - see http://www.spamcop.net/bl.shtml?---

550 [internal] [oob] The response text could not be identified.

Is this related to Marketo's servers, or to the sender servers?

Thank you,

Emilia

[Matjaž_Jaušove2]

Hi Emilia,

not this month, but we experienced similar a couple of times in the past, even with the most engaged lists (and we really try hard not to spam people). It happens, and it is nothing particularly unusual. Also, your bounce rates are still not that hight that you'd need to particularly worry.

It looks your emails were blocked by spam filters. There can be many reasons why this happens, from your email appearing spammy (and trigger spam filters) to misbehaved neighbours (if you are on shared IP).

Additionally, search the community, there are many threads on this topic.

Best;m

[chris_hoh]

Hello @Matjaž_Jaušove2 , are you able to share more insights into the following bounced reasons? Are they mostly tagged to spam? We can't seem to figure out why there is a lot more [oob] . Many thanks in advance!

Email Bounce Category: 9 | Email Bounce Details: 550 [internal] [oob] The response text could not be identified.

Email Bounce Category: 1 | Email Bounce Details: 550 [internal] [oob] The message was blocked by the receiver.

Email Bounce Category: 3 | Email Bounce Details: 550 [internal] [oob] The message failed for unspecified reasons.

Email Bounce Category: 4 | Email Bounce Details: 554 5.4.4 [internal] (last transfail: 421 4.4.0 [internal] no mail servers for this domain could be reached at this time)

Email Bounce Category: 4 | Email Bounce Details: 554 5.4.7 [internal] (last transfail: 421 4.4.0 [internal] no mail servers for this domain could be reached at this time)

Email Bounce Category: 1 | Email Bounce Details: 550 5.7.1 permanently_rejected_message

[Jesse_Richard]

Did you (or an admin) happen to get a blacklist notification from Marketo? (Or are you on a dedicated IP?) Most of those error codes are because you are blacklisted, specifically with SpamCop​; so you may have a spamtrap email address that entered your database recently that you emailed, causing you to get blacklisted (which ISPs use to bounce emails back for suspected SPAM).

[Gursimran_Chand]

Are you on a shared IP? If yes, then this can usually happen.

If you are sending an email using shared IP, there could be hard bounces caused by other customer who share the same range of IP for sending emails. Please refer the below article to know more about how shared IP range works and what are the other possible option you have. 

Link - https://nation.marketo.com/community/support_solutions/blog/2016/02/16/sharing-trust-and-dedication-...

Also, Spamcop listings are temporary and they clear within 24 hours. This means you should be able to resend your email to those addresses affected by this blacklist after the full 24 hour period.