Customers often ask “what are the best configurations to use with PowerMTA”?  En answer is different for every region of the world. Configuration settings in the US will be vastly different than those in Europe for example, so global settings are not as effective. In this blog post, we take a look at five essential PowerMTA™ configuration tips that will help make your sending infrastructure more efficient and reduce I/O clutter.

Utilice las directivas de origen para asegurarse de que las cabeceras de su correo electrónico son correctas

ESPs and many high volume senders send email on behalf of other organizations and often feel they do not have full control over the email headers.   This is not the case, and if best practices are not followed, email almost inherently will end up being routed a la junk folder. With PowerMTA™, you can add missing data or Message-ID headers.  You can also hide internal sources in the “received header,” or completely disable adding the received header altogether. En latter is often used to make it look as if the email originated from the sender’s public IP.

Mantenga una configuración limpia utilizando la herencia de parámetros de forma más inteligente

For manageability configurations, it is important to keep them DRY. DRY stands for Don’t Repeat Yourself, and, is an acronym used by software developers.  For example, PowerMTA™ merges the settings from all matching sources. Thus you can often move common settings a la source 0/0 that matches every IP that connects to PowerMTA™. Except for “always-allow-relaying” of course, which should only be allowed from specific sources. You can also remove settings with obvious default values and further reduce redundant configurations.

With domain directives, all matching domain entries are merged, giving preference to more specific entries, regardless of the order in the configuration. By using sensible default settings for the wildcard domain, you can reduce the configuration to only a few exceptions.  For example, the following setting eliminates the need to enable the use of TLS on “many” specific domains:

<domain *>     use-starttls yes # Use TLS when delivering email </domain>

No malgaste recursos en dominios de correo electrónico no válidos

Si la parte local de una dirección de correo electrónico no existe, normalmente recibirá un mensaje de error del ISP. Sin embargo, si el dominio no es válido, puedes encontrarte con errores repetitivos como búsquedas DNS fallidas, servidores que no responden o servidores que se niegan a retransmitir desde un dominio concreto.

PowerMTA™ should be configured not to waste resources on these domains, and focus delivery of resources to valid domains. You can instruct PowerMTA to bounce email if an MX record could not be found for a domain since invalid domains caused by typos often have an “A “record without a proper “MX” mail server record in DNS. You can also use a domain macro combined with black-holing to drop mail known for discontinued domains or domains with anonymous discardable accounts.  In any event, the goal is to keep the configuration “lean” for invalid or less important domains.

Aplica ajustes basados en tus propios datos y experiencia

We’ve talked about this before, but I’d like to reiterate here.  PowerMTA™ has a long list of configuration directives that you can use straight out of the box. Directly copying settings from other sources or matching configurations from another sender environment is not useful, since you might end up with redundant configurations, or even applying settings that are not applicable in your sending environment. The best approach is to keep it as simple as possible and add settings that you understand, and are appropriate in your “own” environment.

Senders in the US require a different configuration than senders in Europe. Furthermore, the settings often depend on the volume of mail, the type of email, and the reputation of the sending IPs.  You can use data from PowerMTA’s accounting files to determine what are the most important domains in your case. By looking en el bounce reports, you can determine which errors should trigger the back-off mode for example.

Registro de errores transitorios para controlar la estrangulación de los ISP

Los registros contables de PowerMTA™ suelen utilizarse para registrar entregas o rebotes. Pero al habilitar el registro de errores transitorios, puede obtener una gran cantidad de información sobre la entrega, y cómo optimizarla. Los grandes proveedores de webmail, pero también los ISP más pequeños, tienen límites en el número de mensajes que aceptan de una determinada IP. Cuando se alcanza el límite, devuelven un error temporal, que puede ser registrado por PowerMTA™. Esta información puede ser utilizada para ajustar el volumen de IP seasoning (warm-up) o la tasa máxima de envío, o afinar la configuración del modo back-off.

For more comprehensive information on configuration settings, join the PowerMTA forum and don’t hesitate to ask detailed questions about your settings and more specifically about your sending environment.

~ Maarten Oelering, Partner and CTO at Correos