How does Marketo determine an email is invalid?

An invalid email is one that received a 5XX bounce code, which usually means that the email is no longer valid. Yes, they look perfectly valid but let's say it's a work email address and the person left the company and now their email is disabled - it fits the schema of the email addresses but it'll get rejected. The company's email server will send back a special kind of machine-to-machine message stating the bounce code error.

One thing to remember is that bounce code reasons are set by the company, so while the number might be the same the reason syntax might be different.

If you look at this list: https://marketingtechblog.com/soft-hard-email-bounce-codes/   you'll see Hard and Soft bounces, the codes and a basic definition.

Hi John,

Marketo determines an email is invalid in various ways:

• When the lead is created, if the email format is not correct
• When email is hard bounced, which is the case you are mentioning here.

But it can also come from smart campaigns that flag the "email invalid" field.

What is the email invalid cause"?

Please look at the activity log and provide the details (screenshot) of the "email Bounced" activity and that of the "email invalid"

-Greg

Like Robb says, mailservers are free to use any fatal (5xx) error code they want. They don't have to be truthful in the description if they don't like the sender and/or sender's server.

Another edge case in which 5.5.0 can be accurate, but confusing, is when a recipient is redirecting mail to a remote address and that (2nd-hop) address does not exist. Mailservers which have the horsepower to check the remote address in real-time, or which remember that the remote server has been throwing 5.5.0s in the recent past, will send you a synthetic failure because in practice they can't accept mail for that mailbox.

Here's a great example of one that happened IRL.  One of my Product Managers asked why his contact didn't get invited to a webinar.  I looked at the record and saw this:

"Exceeded MaxAttempts - 554 5.7.1 <(removing)@(removed).org>: Recipient address rejected: User not registered with ContentCatcher"

But we had an email from this guy with that same email address just sent to us, which I took to mean that his email server was blocking us.  He checked and sure enough, that was the case.  Here's what he found:

His email system knew it was from Marketo and just blocked it.  He was able to then whitelist the email.

At GE, we have the same system in place that just blocks bulk emails.  Here's a sneak-peek. This doesn't even make it to Outlook, GE blocks it and has it in a hidden area that you have to know about to find it. Ultimately, a lot of companies don't want their employees reading spam, attending webinars and looking at buying products or reading newsletters when they should be working.

We have the same issue. I have a record that is marked as an invalid recipient. However, the contact owner is able to communicate with this person via another sending platform.

We recently ran into a problem with contacts who use Symantec. We did a little research and came across this article on Symantec's website. I am not sure how new this is as part of their AntiSpam service, but it is clearly calling out Marketo sending servers. It just seems to be getting harder and harder to send using tools like Marketo to even communicate with our clients who are subscribed to receive communications. I have notified Marketo support about this and they have pushed it to the deliverability team. Looking forward to what they come up with.