What should we do with mail addressed to our address (street, company number) but where the recipient name does not match? Return it? Open it?

ANSWER

In such a situation, returning the received mail should be regarded as the appropriate course of action. This may be preceded by contacting the sender to inform them that incorrect mail was received. There are no mandatory obligations in this regard, but the action described above should be considered justified. If, without opening the item, you are able to assess that it was sent to you in error, in the author's view there is no need to open it. It should however be emphasised that such a situation constitutes a security incident that the sender of the misaddressed mail needs to assess.