For years Marketo has been developing a database of full email addresses and domains that are determined to be so risky to a customer’s on-going success and the health of the Marketo network that the addresses are never mailed to. Some are unsubscribed from a customer’s database and others are soft bounced, both actions are taken to ensure these addresses are never mailed to out of Marketo.
This is a common practice for Email Service Providers (ESPs) and Marketing Automation (MA) companies. Some prospects see this as a requirement during the pre-sales process to ensure that Marketo is in the business to protect them.
Risky addresses can enter a customer’s database through a number of paths. From just having an older, legacy database that has not been properly managed but these kinds of addresses are most often are introduced through third party and purchased lists.
What kinds of addresses does Marketo block from customer’s mailings:
Addresses of known spam traps and vocal complainers. This list includes full email addresses.
If Marketo’s Email Delivery & Compliance Team is able to identify an address is being used as a spam trap address this is added to Marketo’s Global Blocker. Every night this database is reviewed and if a customer has one of these addresses in their database this is unsubscribed in the customer’s database. The downside with only unsubscribing these addresses is that transactional/operational mail may still be sent.
Addresses from people writing to firstname.lastname@example.org who complain with extreme force or request to receive no marketing mail from Marketo are also added to this database.
Domains of known spam trap and temporary email address domains. This focuses specifically on the part of the email address after the @ sign.
When Marketo’s Email Delivery & Compliance Team identifies that a full domain is being used as part of a spam trap network we are able to take stronger action. Those domains are added to a list within our MTA that recognizes outgoing mail to any address at those domains and responds with a Technical Soft Bounce. This does not set the email as invalid=true in the customer’s database but does prevent the mail from being sent so that the customer is protected from mailing those risky addresses.
Temporary address domains are also added to this database. This includes providers like Mailinator. Experience has proven that these temporary addresses are quickly turned into spamtrap addresses an are often indicative of a poorly collected, maintained and performing database.
Most recently Marketo’s Email Delivery & Compliance Team has been working on the last tier of risky addresses in customer’s databases, generic addresses. This focuses specifically on the part of the email address before the @ sign.
These addresses are viewed as risky because role addresses are built for functions, not people. They’re often forwarded to multiple employees in a company, often change owners, and as a result we often see that these addresses are often a source of multiple complaints for a single email. A number of these addresses are specifically required to be in place by RFC Standards, the "rule book" for the internet, when an email network is put in place. The RFC Standards declare how the addresses should be formatted, what the addresses are supposed to be used for, and which specific roles should use the addresses. As an extension these prescribed addresses should not be on any list used for marketing purposes. Suppressing generic addresses is also a standard practice among ESPs and MAs like Marketo.
Those generic addresses are added to a list within our MTA that recognizes outgoing mail and responds with a Technical Soft Bounce. This does not set the email as invalid=true in the customer’s database but does prevent the mail from being sent so that the customer is protected from mailing those risky addresses.
In addition, we maintain a few logical choices that may cause abuse issues. The list of generic addresses that are being blocked include:
noc, security, hostmaster, usenet, news, www, uucp, ftp, root, spam, spamtrap, honeypot, devnull, dns, phishing, phish, sysadmin, undisclosed-recipients, spearphish, postmaster, spammer, valued.spammer, robot.spammer
Update January 2022: In addition to blocking email from being dispatched to these addresses, Marketo Engage forms will also block these addresses from submission. This will help keep your Marketo Engage database, or other downstream databases, free of non-marketable or potentially dangerous email addresses.
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