结束时不必写“诚挚的祝福”或“谨致问候”之类的结束标识语。

No closing remark such as' Sincerely 'or' Best regards' is necessary.

youdao

你还可以说“谨致问候”，但因为你不知道收信人的名字，而且显然也没有见过他们，所以我认为这个结尾不太合适。

You could also say, "Best regards", but I don't think that would be appropriate because you don't have the name and obviously haven't met them.

youdao

谨致节日问候！

With greeting in this holiday season.

youdao