Email Authentication: SPF, DKIM, and DMARC Best Practices
New SMTP replies at Outlook: update your backoff patterns to avoid reputation damage
2018/04/06 by Willem Stam.
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 […]
Categories: Authentication, Deliverability, General, Providers
AOL and Yahoo merge could impact your email delivery and MTA
2018/02/26 by Willem Stam.
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 […]
Categories: Authentication, Deliverability, General, PowerMTA, Providers
Case study – Why typo domains can cause severe email delivery issues
2018/02/26 by Willem Stam.
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 […]
Categories: Authentication, Case Studies, Deliverability, General, PowerMTA
Happy client: SuccessByEmail.com
2017/11/24 by Willem Stam.
“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 […]
Categories: Authentication, Case Studies, General
Choosing the right DMARC policy
2017/07/13 by Willem Stam.
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, […]
Categories: Authentication, DMARC, General
Five new delivery controls in PowerMTA 4.5
2017/05/26 by Maarten Oelering.
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. […]
Categories: Authentication, General, PowerMTA
How Jobtome replaced 30 Postfix servers with one PowerMTA
2016/06/08 by Willem Stam.
Jobtome helps job seekers access millions of jobs gathered from a hundred thousand recruitment agencyies and employer sites. Jobtome helps companies reach millions of job seekers via pay-per-click based job advertising services. The Challenge: Managing 30 Postfix installations Email is a key business driver within the Jobtome daily operation. The majority of customer interactions are […]
Categories: Authentication, Case Studies, General, Postfix, PowerMTA