When outbound email fails due to a permanent reason (like syntax error), don't retry.

[kfogel]

When an outbound email fails due to a permanent reason -- e.g., syntax errors in the recipient addresses -- then DCSOps shouldn't enter a retry loop. Instead, it should record the details of the failure and reflect the failure somewhere in the UI (where an admin will find out about it).

What happened in issue #232 is a good example of why this matters.