Embassy legalisation for use in Vietnam
Vietnam accepts an Italian document only when a line of signatures connects it to its own mission. Each office in that line vouches for the one before it, and the last mark is made by Vietnam's own staff in Italy. Embassy legalization for Vietnam from Naples is that line, run from the Campania offices rather than the northern ones.
What Vietnam's counter expects to see
The document has to arrive with the Italian stamp intact, the pages fastened as they were released, and the revenue stamp clear of the signatures. Files reassembled after legalisation are refused and have to be run again. Where an application covers several papers, they are lodged as one set so the consular reference stays common to all of them.
The Naples to Vietnam route step by step
One: get or refresh the record so a current signature exists on it. Two: certify it where it is a private paper. Three: legalise the signature at the Prefettura or the Procura della Repubblica, with the €16 stamp attached. Four: lodge the file at Vietnam's consular office in Italy for the closing signature and its fee.
Cost and timing from Campania
The Italian side is fixed and small; the consular side is neither, because a mission sets its own tariff and its own counter days. That is why the 10–15 business day standard is quoted as a range and the express 3–5 track is quoted as a target. A pack of documents costs and waits per item, not per envelope.