Yahoo! Blocks! OSFlash!

If you have a Yahoo Mail email address, chances are you are being kicked out of OSFlash mailing lists as we speak by the Mailman mailing list software that we use. If your favorite list or lists have gone silent suddenly, this is the reason. Until Yahoo! fixes this or tells me what I need to do to fix it, I would suggest that you use a non-Yahoo email address to subscribe to OSFlash mailing lists. Ever since we moved servers, I've been flooded with bounce notifications from the various OSFlash mailing lists with the following error:

SMTP error from remote mail server after initial connection: host []: 421 4.7.0 [TS01] Messages from temporarily deferred due to user complaints -; see retry timeout exceeded

On the linked page it reads:

This error message indicates we are seeing unusual traffic from your IP address and/or that emails from your mail server are generating complaints from Yahoo! Mail users. Please note that this is a temporary error, and we encourage you to retry sending emails to our servers approximately 4 hours after you encounter this particular error.

If you are seeing this error consistently over a 48-hour period, we encourage you to provide us with detailed information, including the complete error message you see in your logs, by filling out this form. (Note: Please make sure to select “Getting deferrals due to user complaints” in the form’s dropdown menu.)

So I filled out the form a few days ago and got this canned email back:


This is an automated message regarding your recent request for Yahoo! Postmaster Customer Care Support. We have received your message but due to a temporary problem we wanted to let you know it could take up to a week until you receive a response. We apologize for this inconvenience.

Thank you for reaching out to us. We look forward to helping you!


Yahoo! Customer Care

**Please do not respond to this message as no one will receive it.

Two days later, I received:


Thank you for writing to Yahoo! Mail.

Please note that if you are not the administrator of the mail server in question, kindly contact your email administrator directly with the error message you are receiving.

If you are seeing a 421 error code in your SMTP logs indicating that the messages you are trying to send are "temporarily deferred due to user complaints," this means that we have observed unusual traffic patterns from your IP address and have been getting considerable complaints from our users regarding emails from your server.

Please note that this is not a permanent error; your system may automatically re-try after a while. We encourage you to try re-sending to our emails approximately 4 hours after you encounter this error. If, however, you are seeing this same error consistently over a 48-hour period, we encourage you to provide us with more information so that we can help diagnose your problem.

For bulk mail senders, please visit the URL below to review our best practice recommendations and request assistance.

If your mail server does not primarily send bulk mailings, please reply to this email and indicate the mail streams that are being sent from your email server(s), e.g., personal/corporate emails, transactional mailings, mailing list postings, newsletters.

Furthermore, if you haven't already done so, please provide the pertinent information about the issue:

a) Detailed description of the problem (including when it started); b) The sending IP address(es) affected; c) Specify all types of emails being sent from the outgoing mail server; d) The specific error code(s) your servers are getting from our MTAs; e) SMTP logs showing the entire mail transcript, from the initial attempt to connect to our MX up until the connection is eventually deferred/blocked.

Your patience during this process is greatly appreciated.

Thank you again for contacting Yahoo! Mail. Your case number for this issue is 46864375. Please reference it in all future communication about this particular issue.


Samuel Cyprian

Yahoo! Mail Customer Care

I've just forwarded this email to my web host and I hope they'll be contacting Yahoo! shortly with the information they require.

In the meanwhile, however, I've started receiving floods of email from Mailman informing me that people with Yahoo email addresses are being removed from various OSFlash mailing lists due to "excessive bounces".

I do apologize if you're affected by this. Please try signing up with a non-Yahoo email address until we get to the bottom of this.

If anyone has any suggestions, etc., please do let me know as I don't grok this stuff at all.