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Check if an email is blacklisted.

I have a customer trying to send email to me using his Yahoo email and he got a bounce.  

What is the best way to see if his email address is being blacklisted?
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strivoliIT Manager

Visit www.mxtoolbox.com and check for Blacklists
Fractional CTO
Distinguished Expert 2019
For the sender john@foo.com, this person can use mxtoolbox (or many other similar services) to check RBL status... which means global blacklisting...

This does not check any Mailbox Provider internal blacklisting. Yahoo is very bad about internal blacklisting...

To check Mailbox Provider status, a test email must be sent as follows...

1) Out the exact IP being used for normal mail sending.

2) With the correct sender + recipient address (same as bounce).

3) The outgoing message must be signed using the exact same DKIM mechanism as usual.

Note: It's usually easier to look at sending mail logs, rather than try duplicating an ad-hoc send for testing.

Note: The only way to know for sure what's occurring is to review the exact send log (if message is blocked upon submission) or the nightly DMARC report (if message is accepted, then a bounce is sent later).

he got a bounce

If you have a Gmail (or other external email account yahoo, etc) have him send the bounce notification to you
The information will be useful in identifying the problem if it's not blacklist or DMARC related.

If you don't have one, you should consider opening one. They come in handy for troubleshooting email issues