Hello Support,

I'm currently trying to send and being blocked from delivery to a domain hosted at Yahoo.

Error message is as follows:

ResponseCode 421, 4.7.0 [TSS04] Messages from 135.84.80.216 temporarily deferred due to user complaints - 4.16.55.1; see https://help.yahoo.com/kb/postmaster/SLN3434.html]


Please let me know if I can provide anything further to help troubleshoot this.

Thank you.