Infrastructure

For an email to be delivered, it must have a valid address that follows certain rules of syntax. Validity Resources Your data quality has a direct impact on your sending reputation and deliverability. Test the accuracy of email addresses in your ...

As a preventative measure against bulking during email delivery, it is critical to ensure that reverse DNS and PTR records are setup and properly configured. The most common reason for establishing a reverse DNS record is to add credibility to the...

One of the keys to effective deliverability is to ensure you are respecting the mailbox providers' resources. Spammers often want to send as much email as possible before a mailbox provider catches them, so they open as many connections to the mai...

List-unsubscribe resources RFC 2369 RFC 8058 Follow the steps below to implement the List-Unsubscribe header for your email program. Talk to your email administrator or email service provider. Inserting the List-Unsubscribe header requires a t...

Forward Confirmed Reverse DNS (FCrDNS) is a DNS technical configuration that shows a relationship exists between an IP address and a hostname. By having FCrDNS, you prove that your IP address is using a sending domain that you own. This relationsh...

An open relay is an improperly configured Simple Transfer Mail Protocol (SMTP) server allowing the unauthorized relay of email. Spammers can connect to the server and use it to send email while forging the sender information of the messages.  Some...

An open proxy is a server that acts as a "middle-man" for requests from one server or network to another server or network and is accessible by any Internet user without restriction. Open proxies do not filter, encrypt, or otherwise check what con...

The key differences between the Mail From (MFrom) address and the From address include: The sending domain of the From address might not be the same as the Mail From (MFrom) domain depending on your sending practices.  During authentication, Send...

The Network Abuse Clearinghouse, A.K.A. abuse.net, is a public database that tracks the contact information of various sending domains. In a nutshell, abuse.net helps forward complaints and abusive activity to network managers, and in turn, these ...

In the most simple terms, your MX records tell the internet where your mail servers exist to receive mail. But why is this important for deliverability? Because it’s also an indicator of where you’re sending mail from.  If your MX records are poo...

The Universal Feedback Loop brings all Validity hosted feedback loops (FBLs) into one cohesive and actionable location. You can use this tool to manage your FBLs, simplify the configuration process, and coordinate subscriptions. You can also group...

When a subscriber marks your message as spam, the mailbox provider sends you back a message using the ARF format indicating that a complaint has occurred. Their expectation is that you suppress that subscriber from receiving future emails. Only ma...

What is a subscriber ID? A subscriber ID is an alphanumeric identifier that corresponds to a specific subscriber in your database. When you receive an ARF message from a mailbox provider indicating a complaint has occurred, you cross-reference the...

The Domain-Based Message Authentication, Reporting, and Conformance (DMARC) authentication standard utilizes both Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) to help determine the legitimacy of an email message. When authen...

Some Simple Mail Transfer Protocol (SMTP) servers are configured to reject your email if the reverse Domain Name System (rDNS) does not match the HELO. It is a best practice to match the HELO and rDNS host name as a part of a properly configured ...

Domain Name System (DNS) changes typically take up to 24 hours to take effect. It is the projected length of time it takes for root name servers and cache records across the entire Internet to be updated with your domain's DNS information.  

There are many different options for Mail Transfer Agent (MTA) software. Some of the more widely used include: Sendmail from Proofpoint Postfix    

Yes, email can be sent from IPv6 IP addresses. Your email server, or Mail Transfer Agent (MTA), needs to support sending from IPv6 and your Domain Name System (DNS) needs to be configured correctly with AAAA records.

At this time, there is no proof that Transport Layer Security (TLS) improves deliverability. However, TLS does ensure the secure transmission of the email as long as the receiving server supports TLS.     

IPv6 uses a 128-bit address which allows for 2128 , or approximately 3.4 x 1038 addresses. 3.4 x 1038 is equal to 340 undecillion IP addresses.  Therefore, there are 340,000,000,000,000,000,000,000,000,000,000,000,000 IPv6 addresses. 

Sender host names must clearly identify their sending identity. When scaling your Mail Transfer Agent (MTA) complexes, you should not overuse the root domain, because this practice raises concerns of spammer-like behavior. Spammers often add chara...