Why are there soft bounces at Yahoo and AOL for opted-in weekly newsletters?

Email marketer from Litmus Blog shares that soft bounces can occur due to temporary issues with the recipient's server or mailbox. However, consistently high soft bounce rates can indicate a more significant deliverability problem that needs attention.

Email marketer from Reddit explains that Yahoo and AOL often implement stricter filtering policies, especially for bulk mail. If your content or sending practices trigger these filters, soft bounces are more likely. They recommend reviewing content and authentication.

Marketer from Email Geeks mentions that the client is not alone in experiencing this issue. The weirdest part is the timing aspect where it sort of turns on and turns off regarding what your client says about it happening once a week then stopping and starting again.

Email marketer from Woodpecker blog explains that a soft bounce indicates an email server accepted your message, but wasn't able to deliver it for a short-term reason - commonly due to server issues, or large emails

Marketer from Email Geeks shares they confirmed it was a lot of TSS04 bounces / 421 errors and that she will submit a ticket via Yahoo Senders Portal.

Email marketer from ActiveCampaign mentions content can be a factor if it is being flagged as Spam - they recommend you make sure the IP address or domain isn't blacklisted

Email marketer from MailerCheck Blog explains that soft bounces occur for various reasons, including a full recipient mailbox, a server being down or overloaded, or the email message being too large. They also state that temporary issues can also cause soft bounces.

Email marketer from Reddit points to potential list quality issues. Even with opt-in lists, addresses can become stale over time. They suggest implementing regular list cleaning practices, such as removing unengaged subscribers.

Email marketer from EmailOctopus Blog explains that soft bounces can result from reputation issues which can be triggered by low engagement and spam complaints. Senders should monitor sending reputation.

Email marketer from SendGrid Blog shares that soft bounces are temporary delivery failures. These can be caused by a full inbox, a server outage, or the message exceeding size limits. SendGrid retries delivery for soft bounces.

Email marketer from Pepipost blog shares that the file size of emails can be an issue - causing soft bounces, especially if you have lots of images. They recommend you reduce the file size.

Email marketer from StackExchange explains that AOL is known to use aggressive spam filtering. They recommend ensuring proper authentication (SPF, DKIM, DMARC) and monitoring feedback loops to identify and address any issues with your sending reputation.

Email marketer from HubSpot Blog explains factors causing bounces can range from invalid email addresses, domain name issues, or that your email server might be blacklisted.

Marketer from Email Geeks responds that the 421 error (soft bounces) are fairly common since around March of this year. They mention others have posted about this, and the advice is to "follow best practices." Yahoo seemingly thinks there is nothing wrong with their current filtering/bounce strategy.

Expert from Word to the Wise explains that soft bounces can be a sign of sender reputation issues, especially with stricter ISPs like Yahoo and AOL. They advise monitoring your reputation and ensuring proper authentication and list hygiene.

Expert from Spam Resource explains that being listed on certain blocklists can cause deliverability issues, leading to soft bounces as ISPs may temporarily reject emails from listed IPs. They stress the importance of monitoring blocklist status.

Expert from Email Geeks says that the TS04 delays kick in easily if your IP and history aren't well known to Yahoo/AOL, and to submit via the sender portal request. If it persists after going through this, it might be more of a list hygiene/data issue.

Expert from Email Geeks explains that it smells like TS04 bounces, a volume spike, and complaints about mail from an IP that Yahoo doesn't know much about. They suggest submitting a ticket via the Yahoo Senders Portal.

Documentation from Mailjet explains that soft bounces can be caused by a variety of issues, including temporary server problems, full inboxes, or content-related issues like spam filters. They are temporary, and Mailjet will try resending.

Documentation from RFC Editor specifies that soft bounces indicate a temporary condition that prevents delivery of an email message. The condition is expected to be resolved in the future, allowing the message to be delivered successfully on a subsequent attempt.

Documentation from Google Postmaster Tools explains that a sender's reputation plays a key role in deliverability. Poor sender reputation can lead to increased filtering and soft bounces. Regularly monitor your reputation using Postmaster Tools.

Documentation from Amazon AWS Documentation explains that soft bounces indicate a temporary problem, such as a full inbox or the recipient server being unavailable. Amazon SES will retry sending messages that result in soft bounces.