Non-error text appearing with -e option

[dominicraf]

When I run emailconverter (at linux CLI) with options -e -a -o -ad, (but not -q). I see non-error output (from SLF4J) like this:

# java -jar emailconverter-2.10.1-all.jar -e -a -o "$DESTFILE" -ad "$DESTDIR" "$NEXTFILE"
SLF4J(W): No SLF4J providers were found.
SLF4J(W): Defaulting to no-operation (NOP) logger implementation
SLF4J(W): See https://www.slf4j.org/codes.html#noProviders for further details.
SLF4J(W): Class path contains SLF4J bindings targeting slf4j-api versions 1.7.x or earlier.
SLF4J(W): Ignoring binding found at [[jar:file:/.../emailconverter-2.10.1-all.jar!/org/slf4j/impl/StaticLoggerBinder.class](jar:file:///.../emailconverter-2.10.1-all.jar!/org/slf4j/impl/StaticLoggerBinder.class)]
SLF4J(W): See https://www.slf4j.org/codes.html#ignoredBindings for an explanation.

This is only tested with 2.10.1 but I expect the same applies to 3.0.0.