Email Deliverability Insights, Tips & Monitoring Strategies
SFR Deliverability: Explaining error codes (GU_EIB) and the ongoing error threshold
2019/10/07 by Jérôme Gays.
Before getting to the actual matter, it is important to brush upon a few relevant chronological events in the past regarding SFR. Even though SFR has been carrying this name since 1987, the many other departments in this group have changed quite a lot ever since. During the past 10 years, SFR has made the […]
Categories: Deliverability, General, Providers
Check your (Power)MTA settings: Numericable and Noos MXs records moved to SFR
2019/09/04 by Jérôme Gays.
In 2014, French ISPs Numericable and SFR merged to become the Altice France group. Numericable was itself the result of a merger between NC Numericable and Noos in 2007. Up to now, mailboxes at these ISPs were managed independently using different MXs and anti-spam protection. Noos and Numericable domains on one end and SFR domains […]
Categories: Authentication, Deliverability, General, Postfix, PowerMTA, Providers
Delivery issues at LaPoste.net resolved
2018/04/10 by Willem Stam.
On Friday April 6, 2018, Postmastery’s Email Delivery Analytics detected serious delivery issues at LaPoste.net. The most frequent SMTP errors we detected were: 421 4.3.2 No system resources 421 4.3.2 All server ports are busy 451 4.7.1 Service unavailable – try again later 421 4.7.0 lpn-prd-vrin0xx Error: too many errors 421 4.4.2 lpn-prd-vrin0xx Error: timeout […]
Categories: Deliverability, General, Providers
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
Deliverability Alert: Orange implements Spam-report based Dynamic Filtering
2015/05/05 by Jérôme Gays.
As SFR did a few weeks ago, it seems that Orange follows the same path towards implementing an email dynamic filtering based on the volume of the generated complaints. This Deliverability Alert is indeed managed by VadeRetro. The anti Spam solution deployed by the main ISP’s and French Webmails, including Orange, SFR, Free and laposte.net. […]
Categories: Deliverability, General