20 tips to keep your newsletter from being tagged as SPAM

Published by Mailrelay on July 11, 2012

After the success of our last article, “How do I know if my newsletter will be detected as SPAM?” in which we explained how to analyze our newsletter’s SPAM score, many of our readers asked us for more tips when creating newsletters.

In Mailrelay, we don’t just want to be the best platform for sending newsletters. We also want to help our customers get the best results from their email marketing campaigns. For this reason, we have compiled this list of suggestions that will without doubt help your newsletters make their way to inboxes, avoiding the SPAM folder. Let’s take a look at these suggestions:


1. The SPF data provided in the Mailrelay welcome email should be included in the SPF record of the sending and replying accounts’ domain provider that you have configured. If the sending domain is registered with ConsultorPC, this domain will be included in Mailrelay’s IP range. If not, you need to contact the domain provider for them to include it. This step will be essential if the –all parameter is configured in your SPF. See more information in this article: “SPF protocol: an ally in the fight against SPAM.”

2. The sending and replying accounts that you have configured must exist, be them forwarding accounts or inboxes. Anti-SPAM filters check to see if the sending and replying accounts physically exist on your server. It is also recommended that you check these accounts periodically, since subscribers sometimes respond to newsletters directly.

3. Source domains should not be newly registered. Most importantly, your domain should have a good reputation; it should not have a history of sending SPAM and it should not be on any black lists. In short, the domain should have a good reputation.

4. These accounts must also have a valid MX record. The MX record shows that these accounts can receive messages, that they are real and can receive email. More information on Wikipedia.

5. Keep your list of subscribers clean, eliminating bounced email addresses, in order to maintain the best reputation possible. If you use Mailrelay, this is done automatically. More information in the article “How Mailrelay manages invalid email address.”

6. Complete the “From” field carefully. Do not leave it empty and avoid using the same name as the email.

7. Avoid using certain words that trigger anti-SPAM filters, such as: “free,” “XXX,” and do not use many exclamation points, question marks or uppercase letters. Whenever possible, avoid pseudo-commercial terms used frequently by spammers, such as “offer”, “opportunity”, “discount”, “money”, etc. Remember that these terms make your SPAM score go up.

8. Never put an image along with a small paragraph or phrase. Spammers use this design very often and it is penalized by anti-SPAM filters, and it makes your spam score skyrocket. This comes from when anti-SPAM filters did not have OCR tools, and it is still in use today. More information on Wikipedia.

9. Avoid heavy use of uppercase letters, especially in the “Subject” line.

10. Avoid SPAM traps. These are email addresses that are not created to be used for communication but rather to attract SPAM (for example [email protected]). We should keep our list of subscribers free of these email addresses.

11. Send the message from a legitimate email address and never from free email accounts such as Terra, Hotmail, or Yahoo! Do not include a paragraph saying that the message is not SPAM. This technique is widely used by spammers and filters look for similar references.

12. Do not overuse text in bright colors. Sharp contrasts in colors are closely analyzed by filter systems.

13. Try to reduce the number of images so that there is more text than images.

14. If you do include images, avoid putting them inside a link. Anti-SPAM filters are suspicious of this practice.

15. Ask your subscribers to add you to their “white list.” This is the most effective way to avoid ending up in the SPAM folder.

16. Use the simplest, raw HTML possible and avoiding using scripts, styles, effects, formulas, etc. You can validate your HTML here.

17. Never send newsletters that contain only images. Anti-SPAM filters consider emails with no text as high risk.

18. Newsletters should contain HTML and plain text versions in the message. By default, the Mailrelay system generates the plain text message from the HTML message. This is most effective because any difference between the two texts can make your SPAM score go up.

19. Avoid sending attachments with your newsletter. Anti-SPAM filters will not look kindly on attachments, and even less so if they are doc, exe, zip, etc. that could contain a virus. It is better for attachments to be uploaded to an FTP with a link in the body of the message for recipients to download. This way you will also get statistical feedback on who opens the file.

20. Follow the laws of your country and international law by including the name of your company, address, telephone number, etc. For example, in Spain, in all of your emails, you must include a legal notice that demonstrates your compliance with the LOPD and LSSI requirements, especially in that referring to communication with recipients from a database that contains personal information, and the recipient’s rights. It is essential that in these rights you include the right to unsubscribe from the newsletter and indicate if he/she no longer wishes to be contacted. This implies that the legal notice should include an effective way for the recipient to communicate this wish, be that an email address to send unsubscribe requests, a link to an unsubscribe form, a notification responding to the unsubscribe request, etc.

By following these recommendations, your SPAM score will stay low and you will have a much higher chance of reaching your subscribers’ inboxes. We hope that these tips are useful in your email marketing campaigns!

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  1. Lilly Hernández

    Muchas Gracias!!!
    Es excelente y bastante clara la explicación. Yo soy torpe con el uso de las computadoras y sin embargo me pareció muy completa y sencilla.

    15/06/2017 - 18:54:50 Publicar una respuesta
  2. Ricardo

    Buenos tips para revisar cuando vas a crear una campaña de email marketing

    23/02/2017 - 09:05:58 Publicar una respuesta
  3. Anurag Gupta

    Nice article ! Need to follow lots of things, specially not to use:
    1. Capital Letter
    2 word like Free, Offer, Opportunity

    Thanks for an excellent write up.

    22/08/2016 - 13:52:46 Publicar una respuesta
  4. Alma

    no entiendo el paso 14.
    Como se supone entonces que voy subir la imagen para que sea visualizada ? esta mal hacer esto http://www.midominio.com/imagen.jpg
    Si me puede explicar es el unico punto que me genera dudas

    17/07/2015 - 07:26:10 Publicar una respuesta
    • Mailrelay

      ¡Hola Alma! No, no, eso es correcto, lo que indica es que no enlaces las imágenes con páginas externas, puedes utilizar imágenes, pero utilizarlas como enlaces puede dar problemas en ciertas situaciones.

      17/07/2015 - 08:02:29 Publicar una respuesta
  5. Marcos

    Cree un boletin, cuando lo envio a mis suscriptores me dice que lo envio perfectamente. Pero solo les llega a los de Yahoo y Gmail, pero no a los de Hotmail o Msn.

    13/03/2014 - 00:55:38 Publicar una respuesta
    • Mailrelay

      ¡Hola Marcos! He revisado el boletín que comentas, si miras en enviados, haces click en el envío y luego en el botón “Envíos detallados” verás que el email dirigido a Hotmail se ha quedado en cola de envío. No ha sido enviado. Lo mejor en este caso es que contactes con nuestro soporte técnico aquí: http://mailrelay.com/es/contacto y les indiques tu cuenta para que puedan ayudarte.

      13/03/2014 - 07:20:48 Publicar una respuesta
    • Mailrelay

      ¡Hola Yesmy! Puedes comprobarlo en el menú de estadísticas de la plataforma, ahí tendrás informes de apertura, clicks y muchas más información.

      17/05/2013 - 11:45:23 Publicar una respuesta
  6. Yhonny

    Excelente Articulo, me aclara muchas cosas, al menos para los emprendedores..Saludos.

    11/03/2013 - 17:41:08 Publicar una respuesta
  7. Javier Mendez


    02/03/2013 - 04:15:01 Publicar una respuesta
  8. Antonio Tadeu Segat

    Li atentamente as dicas e concordo plenamente.
    Se todos levassem em consideração um trabalho honesto, limpo de span e tudo mais, as chances de se ter clientes e amigos se multiplicariam a cada momento.
    Parabéns pelo trabalho.

    18/02/2013 - 14:32:32 Publicar una respuesta
    • Daniel López

      Buenas noches. Excelentes consejos. Sin embargo cuando envío el correo les llegan a mis suscriptores en la bandeja de promociones. No le llega directamente a la bandeja de entrada. Y reviso el informe de Spam y está en 0 ok

      07/01/2017 - 02:14:03 Publicar una respuesta
      • Mailrelay

        ¡Hola Daniel! Sí, si envías promociones, o emails de ventas, los emails van a promociones. Si envías emails sin intención de ventas, solo texto, sin casi enlaces, es más fácil ir a la bandeja.

        07/01/2017 - 09:16:45
  9. Ramiro

    Muy buena guía. Gracias

    01/02/2013 - 22:10:22 Publicar una respuesta
  10. Patricio

    Muchas gracias por la información, Estoy probando vuestro servicio, y por el momento lo veo muy bueno, seguiré los consejos al pie de la letra

    17/12/2012 - 11:58:41 Publicar una respuesta
    • mrblog

      ¡Gracias por los comentarios! Esperamos que te sea muy útil en tus campañas de email marketing 🙂

      17/12/2012 - 12:14:40 Publicar una respuesta
  11. Cabocom

    Las recomendaciones que expone esta documento son muy acertadas. Puede que le falte aconsejar sobre el tipo de lenguaje a utilizar. Pero, de cualquier forma, es muy bueno.

    05/11/2012 - 17:06:35 Publicar una respuesta
  12. julio casanova

    es exelente su servicio

    15/10/2012 - 19:45:14 Publicar una respuesta

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