What technical issues most often masquerade as reputation problems?

Technical issues mimicking reputation problems:

Authentication failures:

Broken SPF causing delivery failures

DKIM signature errors

DMARC misalignment

Looks like: sudden delivery drop, spam placement

DNS issues:

Expired or changed records

Propagation problems

SPF lookup limit exceeded

Looks like: inconsistent delivery, authentication failures

Infrastructure problems:

IP address changes

TLS certificate issues

Server configuration changes

Looks like: blocks, deferrals

Diagnosis priority:

Check technical issues first (faster to identify)

Then investigate reputation

Technical issues are usually faster to fix

Check if the ship is mechanically sound before assuming the harbor banned it.