Emails being marked as spam :(

Level 8

Emails being marked as spam :(

Hey guys,

what are some steps/guidelines to figure out why our emails are ending up in spam inboxes? we recently hosted an event which had poor turn out, and it turns out that most people we invited never saw the email invite because it went straight into their spam folders

is there something we can do to decrease this from happening? are there tools/websites/services available (free or paid) that can help us get to the bottom of this? does MKTO offer anything?

Tags (1)

Re: Emails being marked as spam :(


its good to start with a sound instance and email set-up: Deliverability - Marketo Docs - Product Documentation

When thats in place, there can be very different reasons why deliverability is low for a particular email/list. Search around the nation, there are many discussions on the topic.


Level 4

Re: Emails being marked as spam :(

When we first started our Marketo instance, I found that many of our emails were being rejected as spam. After reaching out for assistance, it was discovered that our emails were rejected due to the servers we were on (as new Marketo customers, I guess?) Our sending process/database info was reviewed, and we were moved to different servers with a 'better' reputation.

Our staying on the better servers is dependant on our using best practices, not spamming, maintaining a high deliverability percentage and not hitting spam traps/honey pots, etc. But that change absolutely solved our deliverability issues, back in the day. Now our deliverablility percentage is a consistant 98 to 99%. 

I'm not sure if Marketo still sets up instances on different servers based upon reputation/performance, etc., but if you review the doc Matjaž Jaušovec referenced and don't see any actions you can take, it might be worth reaching out to your rep or support.

Level 5

Re: Emails being marked as spam :(

The deliverability guide is super helpful! I’d spend some time on reporting to discover if there are trends around specific types of sends and then focus on database cleanup. Let us know if you have specific cases that you need help with!

Not applicable

Re: Emails being marked as spam :(

Read this:Maintaining a Directory of Leads Bouncing Emails

It will explain how to track the lead bounce activity at the lead level. You can then export the data for analysis and figure out what is going on. Chances are the majority of your bounces are Category 1 Hard Bounces i.e. blocked as spam. Marketo suspends sending email to that email address for 24 hours after a category 1 hard bounce but after the 24 hours, the suspension is lifted. That's not enough time to research and fix any issues.

I recommend implementing a quarantine process for those email addresses as opposed to setting Email Invalid to true. I also recommend adding the quarantine flag to your list or segment of Marketable persons that you use when creating email lists. Once quarantined, you can research issues and work with spam blockers and email providers to let them know you're one of the good guys . Then you can reset the quarantine flag to false to resume sending email to that email address.

Even if you can't fix the issue, at least your email deliverability rates improve and help prevent further damaging your sender reputation.

Marketable persons: Black Listed = false, Email Invalid = false, Unsubscribed = false, Email Quarantined = false etc.

Level 2

Re: Emails being marked as spam :(

Hi Malik, is your Marketo instance new? Or have you been sending from it for awhile?

Here are some general things I try when I notice deliverability issues:

  • Check that your sender domains are authenticated (as Matjaz mentioned above).
  • Check to see if you're on any blacklists. I use this tool: Email Blacklist Check - See if your server is blacklisted.
  • Analyze your email delivery/engagement by domain (,, etc.) to help identify any domain-specific issues.
  • Run an email test through a spam testing tool (I like Litmus Spam Testing). I'm new to Marketo, but I believe you can do this through Marketo's "Deliverability Tools" as well.
  • Don't be afraid to suppress stale contacts in your database. Some ISPs (like Gmail) rely heavily on user engagement when deciding whether your emails will reach inboxes. If a large number of your contacts are not opening your emails, you're more likely to end up in the spam folder.

Hope that helps!