upofadown

I use FDM for this. Appropriate parts of my ".fdm.conf":

# Where the bad stuff goes.
action "spam" mbox "%h/Mail/spam"

# Some attachments indicate spam just by existing.
$bad_ext = "*.xlsm"
match attachment any-name "*.xlsm" action "spam"

# Run through spamassassin if not too large.
match size < 500K action rewrite "/usr/local/bin/spamc" continue

# If spamassassin thinks it's spam then good enough for me.
match "^X-Spam-Status: Yes" in headers action "spam"

Requires an actual hardware error. Almost all implementations, including all open source SSH implementations, check that the signature is valid thus preventing a cosmic ray induced bit flip from triggering this issue and any related issue.

What effect do hardware errors have on Ed25519?

RSA is fine. It isn't like you will have to worry about the length of the keys for SSH.