Open a P7M file on Android and iPhone

A signed invoice or contract arrives while you are away from the office. On the phone, a .p7m file does not open in the system PDF viewer. Android and iPhone can show a PDF that has already been extracted. They cannot open the CAdES envelope that contains it. You can still read it from the browser, with a different path on Android and on iPhone. The difference is sharing, not the standing of the document.

Take fattura-2026-014.xml.p7m, attached to a message and saved in Downloads or Files. The reader does not use the name to decide the format. If the content is an Italian electronic invoice, it prepares an organised view. If it is a PDF, it shows the pages. In both cases the file stays on the phone while you read.

Save the right attachment

Before you open the reader, save the file that contains the document.

• On Android, in the mail app, download the attachment to Downloads. If “Open with” offers only unsuitable apps, choose Save and switch to the browser.
• On iPhone, in Mail, hold the attachment and choose Save to Files. Safari does not receive the file from the reader’s Share menu.
• If the message is PEC (Italian certified email), do not save daticert.xml and do not save smime.p7s. Those files describe the transmission or the provider’s signature. The sender’s document is the .p7m inside the original message. Details are in the guide to P7M attachments in PEC.

Some corporate mail apps block download. In that case open webmail in the browser and save the attachment from there. Forwarding the message to a personal mailbox also moves the document data. Do it only if your organisation allows it.

Read in the browser, without installing

1. Open Chrome on Android, or Safari on iPhone, at the reader.
2. Wait for the page to load. The first visit needs a network.
3. Tap the command to choose a file and select fattura-2026-014.xml.p7m.
4. Read the preview and the signers’ details. The preview does not require an account or a payment.
5. If you need to save the original XML, an inner attachment or a printed PDF copy, the reader asks for a license. Plans are on Pricing.

Processing happens in the phone’s browser. The document is not uploaded to a server in order to be read. That applies both to the PDF and to the invoice. The FatturaPA view (Italy’s electronic invoice) shows supplier, customer, lines, VAT and payments by copying amounts from the XML, without recalculating them and without sending the invoice to the exchange system (SdI). For the fields, use the guide to reading an .xml.p7m invoice.

The file may be up to 100 MB. Over 50 MB the reader warns you. On a phone with little memory, close other tabs. For very heavy drawings a Mac is more comfortable: the guide Open a P7M on a Mac uses the same reader, with Finder instead of the phone picker.

Sharing on Android, after installation

The entry in the Share menu does not appear merely because you visited the site. The site’s public manifest does not declare a share target. The sequence is this.

1. Open the reader in Chrome and wait until the page reports offline availability. At that moment the browser switches to the local manifest and the service worker controls the page.
2. Install the reader when Chrome shows the install command, or from “Install app” or “Add to Home screen”.
3. From the mail app, share a single .p7m file and, if it appears, choose Lettore P7M.
4. The service worker keeps the file in memory for about two minutes, without writing it to IndexedDB, the offline cache or a server, then the reader opens it.

If you share more than one file, if the file exceeds 100 MB, or if delivery fails, the message asks you to open the file from the reader. That is not a fault in the document. On iPhone and iPad this path does not exist. Safari does not offer the share target, and adding the icon to the Home screen does not create it. The iPhone path remains Save to Files and then the picker in Safari.

Opening from associated files, where the browser supports it, is a Chromium gesture. Do not rely on it for a company iPhone.

Offline: what stays on the phone

After the first successful load, pages and public resources can be used without a network. You can then select a .p7m that is still on the device and read its content. The cache does not keep opened documents. Closing the tab does not leave a copy you can consult later: to read again you need the file once more.

Revocation may be unavailable offline, even if integrity and the preview are already visible. A missing result does not become a positive one. Authorising a download or a PDF print needs a connection. The license code, if you have already activated it, stays in the browser until you remove it, but the check that authorises export uses the network.

Nested signatures and invoices on a small screen

A name such as atto.pdf.p7m.p7m means several layers. The reader shows them separately. It does not merge them into one signed document. Countersignatures stay unverified. If the layers exceed the allowed maximum, opening stops with a message about nested signatures, not with a partial PDF.

On the invoice, check VAT number, document type, withholding tax, pension fund and IBAN before you authorise a payment. Inner XML attachments, if present, download with a license. Compressed ones stay in the compressed format, without automatic decompression. An unreadable attachment remains in the original XML anyway.

If the phone says the file does not look like a P7M, see the guide A P7M file will not open. The most frequent causes are a truncated download, a renamed PDF or non-standard Base64.

Example: the invoice arrives at 18:00

It is 18:00 and the supplier sends fattura-2026-014.xml.p7m, about 180 KB. On the Android phone, open the message, save the attachment to Downloads and do not tap “Open with” if it offers a PDF viewer. In Chrome, go to the reader, choose the file and wait for the invoice view. Check the total and the IBAN before you forward a screenshot to the person who pays: the screenshot is not the envelope and it is not the XML.

If you have already installed the reader after offline preparation, you can instead share that single file from the mail menu. If the entry does not appear, do not reinstall at random. Open the reader, wait for offline availability and try again, or go back to the picker. A second attachment in the same share is rejected. Open it on its own.

On a colleague’s iPhone the same mail must be saved to Files and opened from Safari. The Home icon, if added, is only a shortcut to the site. It does not put Lettore P7M among the Share destinations. If the colleague is on a train without a network, reading a file already saved works only if the site was loaded before, with local handling active. Revocation may stay unavailable until the connection returns. Exporting the XML waits for the network and for a license.

Frequently asked questions

Do I have to install an app from a store?

No. You can read the file in the browser, without an account. Adding it to the Home screen is optional and, on Android, it is the step that can enable sharing.

Does sharing also work on iPhone?

No. The iPhone and iPad Share menu does not deliver the file to the reader. Save the attachment to Files and select it from Safari.

Can I open a P7M without a connection?

After the first load, if local handling is active, you can choose a file that is still on the phone. Documents are not kept in the cache. Revocation may be unavailable and export needs the network.

Does the reader sign documents from the phone?

No. This guide is about reading. To sign, you need a certificate issued by a qualified provider, using the tool that provider supplies.

What to do with the file you have read

Use the phone to read and to check the signer and the certificate status. Keep the original .p7m. If the revocation result is ambiguous, do not interpret it alone: the guide Expired or revoked signature separates a claimed date from verified time evidence. To apply a signature, rather than read one, start from How to get a digital signature in Italy.