I sent out a group email yesterday and all of the ones with Yahoo email addresses came back with this message:
This is the mail system at host gateway13.unifiedlayer.com.
I’m sorry to have to inform you that your message could not
be delivered to one or more recipients. It’s attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
I found some discussion here that seems to indicate that i “need to configure an outgoing rate limit on Postfix for all Yahoo domains” - https://serverfault.com/questions/995731/emails-are-getting-temporarily-suspended-from-yahoo-and-yahoo-doesnt-give-a-dam
If you agree that that is what I need to do can you help me figure out how to do it at MXRoute?