SmartLockr SMTP Relay Service

E-mail messages can face obstacles during sending. The SMTP Relay Service ensures that messages will be sent and delivered securely.

SmartLockr Relay Service

What is an SMTP Relay Service?

SMTP stands for Simple Mail Transfer Protocol and it is the way an email message is sent over the internet. In other words, when you send an email, this message leaves your server and is then delivered to the recipient's inbox. Only, when a message is sent, it can sometimes run into obstacles. This ranges from poor delivery options to blocked IP addresses, which means that emails can’t always get through. As a user, we don’t see the process of a sent email, but we understand if there has been a problem, when we receive a notification that the message couldn’t be delivered.

To ensure that this process runs smoothly and messages are delivered, an intermediary is required: this is what the SMTP Relay Service involves. The Relay Service ensures that the sent emails, where necessary, receive the correct adjustments to be delivered.

"The SMTP Relay Service ensures the secure sending and delivery of emails"

How does the Relay Service work?

The email application you use sends the email message, connecting to the Relay Service. With the sent email, there are details that included: All this information is required by the Relay Service to determine how the message will be sent and to whom. The message can be sent directly to the recipient (“Message Delivery Agent”) or it takes several ways before it reaches the recipient's inbox.

The purpose of the Relay Service is simple, it ensures that all sent messages can be forwarded and arrive securely at the recipient.

What does the SmartLockr Relay Service do?

SmartLockr also uses an SMTP Relay Service. It ensures that messages are sent and delivered to the recipient with proper security. SmartLockr also offers applications, that send e-mail messages that don’t have the correct email routing,  to use this technology. The easy thing about the SmartLockr Relay Service is that it is configurable. SmartLockr can be adapted to the needs of the organization. The behavior of the SmartLockr SMTP Relay Service can be influenced by means of “headers” - which can be used to indicate configurations. In other words, depending on the settings made, the Relay Service will apply appropriate security.


How does it work exactly?

The principle is simple: an email that is sent is viewed on its way. It will be determined what to do next. This is what it looks like:

SMTP Relay Service SmartLockr

As a sender or recipient, we don’t notice this, but the Relay Service does its work in the background. For SmartLockr this means the following:

  • Messages are always sent with the correct security. This can be one-factor authentication or two-factor authentication when it comes to the transmission of privacy-sensitive data;

  • The Relay Service can be triggered by contentpolicies, such as words or regular expressions. This may be desirable for the NTA 7516 compliancy, as it transmits health data through the most secure way. Suppose you send an email with content triggers that are included in the content policy, then SmartLockr will secure the message and deliver it according to the standards of the NTA 7516. In all other cases, the message will be sent as presented;

  • The Relay Service can be disabled if recipients come from a specific domain or on listed on a certain white list. In this case, emails are already sent securely, after which the Relay Service doesn’t have to offer custom security. The administrator easily manages these settings in our cloud-based administrator portal.


SMTP SmartLockr Relay Service


Our Difference

If you choose SmartLockr, you choose safety and convenience. We make the difference by:


Communicate securely without disrupting your and your employees' work processes. Our solution is very user-friendly, which means that it is actually used.

Increasing awareness

If you, as a user, are more aware of what you are doing, the chance of an error is reduced. This can prevent data from being sent to the wrong person.

Comply with regulations

With the use of SmartLockr, you comply with regulations, like the GDPR. This means that you always work according to the applicable standards, without having to take extra measures.

Are you interested in our SMTP Relay Service and do you see business opportunities?

Our Development Partner program allows you to easily integrate secure email with your application – which enables secure communication to your customers as well.

Become a partner