Fax, email or registered mail
Seven criteria, three channels, and the question that actually decides.
The right channel depends on what you may need to demonstrate later. Email is the fastest and the most convenient, but it can be filtered out without your knowing. Fax gives you a confirmation issued by the receiving device itself, in one to two minutes and free of charge. Registered mail is the slowest and the only paid option, but it is the one the law frames most precisely. In practice the question is almost never which is best: it is what your recipient accepts, and what you will have to prove.
The comparison
Seven criteria that genuinely make a difference in use. The cells say what each channel does, not what it promises.
| Criterion | Fax | Registered mail | |
|---|---|---|---|
| Delivery confirmation | Issued by the receiving device, page by page. | Optional read receipt, which the recipient can switch off. | Proof of posting and of delivery issued by the postal operator. |
| Silent failure possible | No. The transmission either succeeds or reports its failure. | Yes. Spam filtering, a security gateway or a rejection with no reliable notice. | No. An uncollected item goes back to the sender. |
| Speed | One to two minutes. | A few seconds. | One to several working days. |
| Cost | Free on MondialFax, with no quota and no registration. | Free. | A few euros per item. |
| Sender identity | The calling number travels with the page. Spoofing an assigned line is hard. | The sender address can be forged; SPF and DKIM reduce the risk without removing it. | Identity recorded at posting, depending on the option chosen. |
| What actually travels | An image of a page. No executable file, no clickable link. | Any format, with attachments sometimes blocked on the way. | Paper, or an electronic item depending on the option. |
| Accepted by organisations | Frequently requested in healthcare, the courts and public administration. | Varies from one organisation to the next, often refused for formal filings. | Required whenever an act must be formally served. |
When to choose which
Use email
When speed matters, when your correspondent will reply anyway, and when nobody will have to demonstrate anything six months from now. It is the default channel, and rightly so.
Use fax
When the recipient gives you a fax number — they are the ones who decide — when you want an immediate confirmation from their own equipment, or when your document should arrive without passing through a hosted mailbox.
Use registered mail
When a statute, a contract or a procedure names it explicitly, or when the date of receipt will have to be enforceable. The delay and the cost are the price of a far more precise legal framework.
On legal weight, let us be precise
None of these three channels has "the" legal weight in the abstract: it depends on the country, on the type of act, and on what the applicable contract or statute provides. What is true everywhere is that you can only properly prove what you kept a record of — and the three channels do not produce the same record.
A fax produces a transmission report issued by the receiving machine. Email produces technical headers and, possibly, a read receipt the recipient controls. Registered mail produces a document issued by an independent third party, which is precisely what the law recognises in it. If your item could end up in front of a judge, ask a legal professional which channel your situation requires: this page compares technical properties, it is not legal advice.
Frequently asked questions
- Is a fax worth more than an email?
- It produces a different record, issued by the recipient's equipment rather than by an intermediate server, and it cannot be filtered out silently. Does that make it worth more before a judge? That depends on the country and the type of act, and it is a question for a legal professional rather than for a technical comparison.
- Can I replace registered mail with a fax?
- Not when a statute or a contract names registered mail explicitly: in that case no other channel will do. Fax is a sound alternative when the goal is to get a document quickly to a recipient who asks for it by fax.
- Why do some organisations still ask for a fax?
- Because the confirmation comes from their own equipment, because the document does not land in a mailbox hosted by a third party, and because their internal procedures have relied on it for a long time. The recipient sets the channel, never the sender.
- Is fax safer than email?
- On one specific point, yes: what travels is an image of a page, with no clickable link and no executable file, which removes the most common phishing vectors from the channel. In exchange, a received page sits printed on a device other people can read. Both channels have weaknesses, but not the same ones.
Continue exploring
The most useful pages to carry on with your fax.