The mda-lmtp tests are missing a file in the repository, which causes the
test to fail. This went unnoticed because they are not included in the
automated test suite, which will be fixed in a follow-up patch.
This patch adds the mising test file, with a harder to miss name.
Either the recipient or from addresses can be "<>" to indicate the null
address. mda-lmtp does not handle that well, as it sends "<<>>" which is
invalid.
This patch fixes that by special-casing them, which is unfortunate but
reasonably common.
