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How to troubleshoot and resolve soft bounce issues with Yahoo/VZG email delivery?

Summary

Soft bounce issues, particularly with Yahoo and Verizon Media Group (VZG) domains (like Yahoo, AOL, and others), are a common challenge for email senders. These temporary delivery failures, known as deferrals, indicate that the recipient's server temporarily rejected the email, often due to perceived sender reputation, content issues, or list quality problems. While frustrating, they offer an opportunity to identify and rectify underlying deliverability issues before they escalate to hard bounces or blocklisting.

What email marketers say

Email marketers often find soft bounces to Yahoo/VZG domains perplexing, especially when other mailbox providers accept their mail without issues. Their experiences highlight the importance of diligent list management and an awareness of how content, including linked assets, can affect delivery. Many marketers suspect that the primary issue lies with the quality and engagement of their recipient lists, leading to senders being advised to adopt stricter list hygiene practices. Additionally, an unexpected factor like a change in CDN can sometimes lead to sudden and persistent deliverability problems.

Marketer view

Email marketer from Email Geeks suggests that their gut feeling points to senders not removing stale email addresses quickly enough, leading to a continuous push of traffic to old, non-responsive recipients as the root cause for Yahoo/VZG soft bounce issues.

23 Sep 2020 - Email Geeks

Marketer view

Email marketer from Email Geeks notes that when they see persistent soft bounce issues, it is primarily due to the sender's list quality, requiring them to engage clients to tighten up their recipient lists.

23 Sep 2020 - Email Geeks

What the experts say

Experts emphasize that Yahoo/VZG's filtering goes beyond simple list hygiene, delving deep into message infrastructure and content. They point out that VMG (Verizon Media Group) analyzes the full message, including links and even image patterns, before issuing a temporary failure. This sophisticated analysis means that underlying issues like problematic content or unexpected changes in how assets are hosted (e.g., via a CDN) can lead to deferrals. For ESPs, experts recommend treating persistent soft bounces as triggers for thorough compliance investigations.

Expert view

Expert from Spamresource.com states that email providers use sophisticated filtering techniques to combat spam, including the ability to identify identical messages sent from different IP addresses and domains.

20 Feb 2023 - Spamresource.com

Expert view

Expert from Wordtothewise.com highlights that spammers often use image-only emails to bypass traditional text-based filters, leading mailbox providers to develop defenses that apply to all mail, even legitimate senders.

10 Jan 2023 - Wordtothewise.com

What the documentation says

Official and industry documentation consistently highlights the importance of sender reputation, list quality, and compliant content for successful email delivery. For Yahoo and VZG properties, specific emphasis is placed on minimizing spam complaints, managing deferral rates, and ensuring proper authentication. Documentation often details the various reasons for soft bounces (e.g., temporary server issues, recipient inbox full, reputation-based deferrals) and provides general best practices to improve deliverability to their domains. They underscore that mailbox providers are constantly adapting their filters to combat evolving spam tactics, requiring senders to remain vigilant.

Technical article

Documentation from Mailgun states that soft bounces often stem from temporary issues like a full inbox, server downtime, or the recipient's server flagging the email as suspicious.

10 Apr 2024 - Mailgun

Technical article

Documentation from SendLayer advises that understanding the specific SMTP error code and message is critical for diagnosing the underlying cause of a soft bounce, as there isn't one universal reason for their occurrence.

20 Nov 2023 - SendLayer

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