Emails not delivering to Yahoo (and probably others...?)

Emails not delivering to Yahoo (and probably others...?)

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 [TS01] Messages from 74.201.154.126 temporarily deferred due to user complaints - 4.16.55.1; see https://help.yahoo.com/kb/postmaster/SLN3434.html]

For the time being I've switching SMTP servers to another provider, but I'd like to get back to using Zoho as soon as possible.

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

Thank you.