Email Authentication: SPF, DKIM, and DMARC Best Practices

Postmastery supports SendGrid clients with multiple webhook endpoints

Postmastery provides delivery monitoring and optimisation services on top of various email delivery environments. Sometimes we offer this service on top of on-premises MTA (like PowerMTA or EmailSuccess) and sometimes on top of cloud-based ESP’s (like Mailchimp or Smartfocus). A prerequisite of delivery monitoring and optimization services, is to get the right data points like […]

Read the complete article

Categories: Authentication, General, Sendgrid, Solutions

New SMTP replies at Outlook: update your backoff patterns to avoid reputation damage

On April 5th, at 5AM CET, we were alerted by a huge spike in Outlook deferrals. The chart below (copied from Postmastery Delivery Analytics) reveals the deferrals over time: After investigating the issue, Postmastery delivery engineers discovered new SMTP replies at Microsoft domains. These errors are receiver’s side, not related to sender’s reputation. Organization queue quota […]

Read the complete article

Categories: Authentication, Deliverability, General, Providers

AOL and Yahoo merge could impact your email delivery and MTA

A few weeks ago, AOL reported that AOL and Yahoo will come together under the OATH umbrella and merge with the Yahoo email infrastructure to serve both brands. This happened on 20 February 2018, and now all the AOL recipient domains’ MX, including the following, will point to mx-aol.mail.gm0.yahoodns.net: – aol.com – verizon.net – aol.co.uk […]

Read the complete article

Categories: Authentication, Deliverability, General, PowerMTA, Providers

Case study – Why typo domains can cause severe email delivery issues

In our daily email delivery monitoring activities, we recently saw the damage that typo domains can do. In this case study, simple typos in domains caused severe email delivery issues. We will recap what happened and how we solved the issue. Hopefully, other senders can avoid this kind of situation in the future. Postmastery, we […]

Read the complete article

Categories: Authentication, Case Studies, Deliverability, General, PowerMTA

Happy client: SuccessByEmail.com

“I would like to thank the PowerMTA email delivery experts at Postmastery. Postmastery was incredibly responsive to our specific delivery needs and wasted no time in taking a scientific approach to identify specific issues and formulate a path to resolution. From precise data collection and analysis to resolution recommendations and follow up, Postmastery does a […]

Read the complete article

Categories: Authentication, Case Studies, General

Choosing the right DMARC policy

Publishing DMARC records is more popular than ever. Even among those that don’t have domains related to sensitive fields, such as financial institutions, that are vulnerable to abuse. Have you thought about the policy that underpins your objectives for DMARC? Do you even have clear objectives for DMARC? DMARC policies DMARC requires three policies: none, […]

Read the complete article

Categories: Authentication, DMARC, General

Five new delivery controls in PowerMTA 4.5

PowerMTA (PMTA 4.5) always had a strong focus on ‘doing one thing, and doing it right’. That one thing is email delivery. This sounds like a simple task, but it is hard to do at scale, both in terms of volume as well as in terms of the differences in the behaviour of receiving systems. […]

Read the complete article

Categories: Authentication, General, PowerMTA

There are many more interesting blogs by category for you to read.