This option came from Spree and we never used it. The config input field
is disabled in the admin interface and I checked our managed databases.
I don't think that we will want this feature in the future either.
Staging sends unmodified emails which is more realistic and we haven't
had a use case to intercept those emails. There's still the BCC option
if we need additional access.
Previously we only set these part-way through deployment, so the values could be out of sync between our ENV vars and Spree::Config (which itself is a mix of both cached values and database-persisted values).
