Why Mailtrap Updated its SMTP Host

March 9th, 2018

Categories: Development, Testing

In today’s post, our team would like to share additional information about the recent SMTP host update, as well as confirm our commitment to building a reliable dev tool that all Mailtrap users can enjoy!

The Story:

  • Back in March 2016 a Mailtrap user, Marc, submitted a request via User Voice where he said that by pointing to the “mailtrap.io” domain, some mail-related software automatically looked up the domain’s MX records. As a result, the system provided a response that led to Google’s servers since they handled Mailtrap’s company-related mail. In order to resolve the issue, the same user recommended that we maintain an alternative domain name, like “smtp.mailtrap.io” that would have no MX records at all.

  • On 10 November 2016 our team introduced the new SMTP domain client - “smtp.mailtrap.io”, as well as enabled MX record support. This was the day when the changes were applied to the application itself. The announcement was published in the Mailtrap Change Log. Therefore, all new clients who signed up after this date automatically got the new SMTP credentials with enabled MX record.

  • As a result, when the load on the SMTP servers grows, our team can scale the SMTP backend, which will not affect the web backend performance at all. In addition, after enabling MX records, when software looks up the domain’s MX records, the system directs to the Mailtrap servers.

$ nslookup -type=mx smtp.mailtrap.io
Server:        192.168.1.1
Address:    192.168.1.1#53

Non-authoritative answer:
smtp.mailtrap.io    mail exchanger = 10 smtp.mailtrap.io.
smtp.mailtrap.io    mail exchanger = 50 smtp1.maltrap.io.

Authoritative answers can be found from:
  • In the end of November - beginning of December 2017 our team ran an email campaign that informed all users about the new email forwarding feature, as well as communicated our intention to block traffic from “mailtrap.io”.

  • On 8 March 2018 Mailtrap blocked the traffic from “mailtrap.io”

Mailtrap Recommendations

  • The Mailtrap users who signed up for Mailtrap before November 10th, 2016 and did not update their credentials have to make a slight change in the SMTP host address: add “smtp” to the current SMTP host name. So, instead of “mailtrap.io”, it will be called “smtp.mailtrap.io”

Mailtrap SMTP host credentials

P.S. If you have any questions or concerns about the new features described in this blog post, please feel free to send them to support@mailtrap.io and our team will be happy to assist.