Breakdown of Handys sind strengstens verboten, außer wenn der Moderator es erlaubt.
sein
to be
es
it
das Handy
the cellphone
verbieten
to forbid
Questions & Answers about Handys sind strengstens verboten, außer wenn der Moderator es erlaubt.
How do I know whether to use außer wenn or außer dass?
Use außer wenn for conditions (meaning "unless" or "except if"). Use außer dass to state a factual exception (meaning "except that"). Here, the host allowing phones is a condition, so außer wenn is the right choice.
Why is the verb erlaubt at the very end of the sentence?
The phrase außer wenn acts as a subordinating conjunction. Just like weil or dass, it sends the conjugated verb (erlaubt) to the end of its clause.
Why does streng have an -stens ending here?
The -stens suffix turns the adjective into an absolute superlative adverb, meaning "to the absolute highest degree." The phrase strengstens verboten is a very common fixed expression for "strictly forbidden."
Does Moderator only refer to an internet forum moderator?
No, it is actually much broader. In German, a Moderator is the standard word for a TV or radio host, a presenter, or an event facilitator.