Managing Sender Reputation at the Local Level: Automatic Back off Mode Part II | Port25 Solutions, Inc.
Fred Tabsharani
VirtualMTA Technology

By port25admin

Managing Sender Reputation at the Local Level: Automatic Back off Mode Part II

Traffic_lights_4_statesLast week we introduced you to an essential PowerMTA feature called Automatic Back Off Mode:  In part II, we’ll discuss this feature in more detail and how it can dramatically improve sending in your local environment.

In order to manage sender reputation effectively, commercial MTAs use features to throttle mail. Some products are reactive in nature, while others are proactive.  Reactive products attempt to “tune” settings based on a continuous series of connection guesstimates. You start with trying to open, say, 100 simultaneous connections to a particular MX (or domain) and then observe what happens. If an error is returned, then the algorithm tries fewer connections- rinse & repeat. In these cases, the goal is to ascertain the “right” connection settings such that errors are generated less frequently.

We believe this is essentially a reactive approach to optimizing and preserving sender reputation.  If an error is given at the handshake to indicate the sender is attempting too many connections, some commercial MTAs will throttle down to whatever alternative setting has been configured.

What sets PowerMTA apart?  PowerMTA prefers to err on the side of having the deliverability manager make such decisions rather than an arbitrary algorithm.  The main difference between Port25’s Automatic Back-Off Mode and other services, is that rules and configurations are managed locally by the administrator, or deliverability engineer as opposed to a central service, since these systems cannot necessarily or optimally adapt to the “local” environment, thus making them reactive.

Optimal delivery configurations differ in every region of the world or with every type of sender. With PowerMTA, you can granularly tune your settings to the local environment, and that is often what deliverability administrators require, depending on region and customer type (B2C, B2B).

According to feedback from the field, delivery administrators prefer to calibrate rate-limiting gradually, which in this case means deliverability consultants that have worked with both PowerMTA and other commercial MTAs.  Maarten Oelering of PostMastery a well known deliverability consultants who specializes in email infrastructure said, “We’ve seen IP warm-up rules in other commercial MTAs’ systems, which are very “binary” and unrelated to ISP feedback from local data, which is in contrast to PowerMTA’s ability to use that feedback and adapt to different environments.”

PowerMTA offers more than just “backoff”. It can also disable IPs in a load-balanced pool of IPs, and it can bounce individual mails based on specific temporary errors, such as “quota exceeded” errors reported as a temporary (4xx) error. We believe the main advantage of PowerMTA is “simplicity” and “control”. It is not overly complex and you’ll find that having more independence allows delivery administrators to be in full control. From the field, we’re noticing that more and more delivery engineers are finding themselves less obsessed with ISP policies. Certainly configuration is a discernable part, but the right configuration is often a lot simpler than most might think.

When the automatic back off feature is triggered, your email sends will be more successful, ultimately preserves each individual mail stream along with your sender reputation. One of the keys to maximizing email deliverability to valid domains is to know immediately when specific delivery issues are occurring within your queues. Having real-time visibility into queue performance is essential. The sooner a delivery expert realizes that there are definite problems, or more specifically, that a remote site or ISP is rejecting your messages, the sooner one can attempt to get the problems resolved.

There are many different kinds of error messages that remote sites will respond with when simultaneous connections are made. These responses allow you to directly see your current sender reputation, in the eyes of that recipient domain or mail gateway.  Through this intelligent process, mail-streams will be reshaped, throttled, resulting in higher deliverability rates.  PowerMTA™ includes automated sender reputation monitoring, via an advanced, real time SMTP command monitoring implementation. It not only gives you an early warning alert system for specific types of error messages, but it can be configured to resolve some problems as well, via support for automated configuration changes for future delivery attempts.

In Part III of this blog series on Automatic Back Off Mode,  we’ll discuss a few rules you can implement when “back-off” is triggered, along with VirtualMTA Groupings and Queue Modality.

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