LMTP connection failures return 554 instead of 450 (regression in 0.9.5) #872

When we bounce our LMTP server, maddy now (as of 0.9.5) rejects RCPT with:

554 5.0.0 Internal server error

Previously, it returned a temporary error, so senders retried:

450 4.4.2 Network I/O error

The result is that we are losing some inbound emails.

Agent says:

fd6d880 changed attemptConnect in internal/smtpconn/smtpconn.go to wrap dial errors as fmt.Errorf("dialer: %w", err). wrapClientErr checks for *net.OpError with a plain type switch, so it no longer recognizes the wrapped error and falls through to the default case, which ends up as a 554. Reverting that line restores the 450. Using errors.As in wrapClientErr would also work and would keep the extra context.

Thanks!