The basic process: email to fax gateway

You send a fax by email by using a fax-to-email gateway — a service that converts your email into a fax and delivers it to a fax machine on the other end. Instead of dialing a fax number, you address an email to a special email address that includes the recipient's fax number, attach your document, and send it. The gateway receives your email, converts the attachment to fax format, and transmits it through the phone line to the destination fax machine.

The recipient sees a standard fax arrive at their machine — they don't receive an email. From their perspective, the fax came through normally. This method works whether the other person uses a traditional fax machine, a multifunction printer with fax capability, or a fax modem connected to their computer.

Most fax-to-email services are free for a limited number of faxes per month, with paid plans available if you need to send more. Some services charge per page rather than per fax, so a five-page document counts as five pages, not one transaction.

Key Takeaways

  • You send a fax through email by addressing it to a special email address that encodes the recipient's fax number, then attaching your document and sending it normally.
  • The most common free services are eFax, Google Fax, Fax.plus, and HelloFax, each with different monthly page limits before charging begins.
  • Your document must be in a format the gateway accepts — usually PDF, Word, or image files — and you should keep file size under 10 MB to avoid rejection.
  • The fax arrives at the recipient's machine within minutes, and you receive a confirmation email showing whether delivery succeeded.
  • If you send faxes regularly, a paid plan or a dedicated fax service may cost less than paying per-page fees over time.

Choosing a fax-to-email service

The service you choose depends on how many faxes you send each month and whether you need to receive faxes as well. eFax allows 10 free pages per month before charging; Google Fax (through Google Voice) is free for calls and faxes within the US; Fax.plus offers 2 free faxes monthly; and HelloFax provides 5 free pages per month. Each has a different interface, so the one that feels easiest to you matters more than which has the most features.

If you send faxes only once or twice a year, a free tier is usually enough. If you send several faxes each month, calculate whether a paid plan saves money compared to per-page charges. A paid plan typically costs $10 to $20 per month and includes 100 to 500 pages, which breaks down to roughly $0.02 to $0.10 per page — cheaper than paying $1 per page on a free tier once you exceed the limit.

Some services bundle fax-to-email with email-to-fax (receiving faxes as PDFs in your inbox), while others do only one direction. Decide whether you need both before signing up, because switching services later means updating the fax number you give to people who send you faxes.

Setting up your first fax through email

Start by creating an account with your chosen service — most require only an email address and a password. The service will assign you a fax number (if you're receiving faxes) or show you how to format the recipient's fax number into an email address. For example, with eFax, a fax to 555-123-4567 becomes 5551234567@efaxsend.com. The exact format varies by service, so check their instructions for the correct syntax.

Prepare your document in a format the service accepts. PDF is the safest choice because it preserves formatting and works with every service. Word documents, JPG images, and PNG files also work with most gateways. Avoid sending documents larger than 10 MB, as many services reject oversized files automatically. If your document is a scan, make sure the text is dark enough to read — faxes transmit in black and white, and light gray text may not come through clearly.

Open your regular email (Gmail, Outlook, Yahoo, or any other provider), create a new message, and address it to the fax email address you created in the previous step. Type a brief subject line — the recipient's fax machine won't display it, but it helps you track the fax in your sent folder. Attach your document, add any message you want in the body (though many fax machines won't display it), and send the email as you normally would.

What happens after you send the email

The fax-to-email gateway receives your email within seconds and begins converting your attachment to fax format. This usually takes one to five minutes. Once the conversion is complete, the service dials the recipient's fax number and transmits the document. If the line is busy or the fax machine is offline, the service typically retries automatically — usually three to five times over the next hour or two.

You'll receive a confirmation email from the gateway showing whether the fax was delivered successfully. This email includes the time sent, the recipient's fax number, the number of pages transmitted, and whether any errors occurred. Keep this confirmation in case you need proof the fax was sent. If the delivery failed, the confirmation will say so and may suggest why — for example, "fax machine did not answer" or "invalid fax number".

The recipient sees the fax arrive at their machine just as if you had sent it from a traditional fax machine. They won't know it came through email unless you tell them. The fax will include a header showing your fax number (the one assigned by the service) and the time it arrived.

Common problems and how to fix them

If your fax doesn't go through, the most common cause is an incorrect fax number. Double-check the number against the original source — a missing digit or a transposed number will cause the gateway to dial a wrong number. Fax numbers in the US are 10 digits; if you're sending internationally, include the country code (for example, 44 for the UK) at the beginning.

The second most common issue is file format or size. If the service rejects your attachment, try converting it to PDF using a free tool like Smallpdf or ILovePDF, then resend. If your document is a large scan, compress it before attaching — most email providers and free tools can reduce file size without making the document unreadable.

If the fax number is correct and the file is acceptable but delivery still fails, the recipient's fax machine may be offline, out of paper, or in an error state. Ask the recipient to check their machine and try again. Some older fax machines also have trouble receiving from internet-based services, though this is rare. If the problem persists, contact the recipient by phone to confirm the fax number and ask them to check their machine's error log.

When to use fax email instead of a traditional fax machine

Fax-to-email is faster than walking to a physical fax machine, works from anywhere you have email access, and creates an automatic record in your email folder. You don't need to own or maintain a fax machine, and you can send a fax at midnight without disturbing anyone. If you send faxes only occasionally, this method costs nothing or very little.

The main limitation is that you can't send a physical document without scanning it first. If you have a stack of papers to fax, scanning each one takes time. In that case, a multifunction printer with a built-in fax function may be faster. However, if your documents are already digital — a PDF, a Word file, a screenshot, or an image — fax-to-email is usually the quickest path.

Fax-to-email also works better than traditional fax for sending multiple copies to different recipients. Instead of dialing each number separately, you send one email to multiple fax addresses, and the gateway handles the rest. This is especially useful if you're sending the same document to several people.

Frequently Asked Questions

Can I send a fax to an email address instead of a fax number?

No. Fax machines and email are separate systems. If someone gives you an email address, send them an email directly — don't try to fax it. If they gave you a fax number, use a fax-to-email service to send it to that fax machine. The two are not interchangeable.

What if the fax number has letters in it?

Fax numbers contain only digits. If you see letters, they represent numbers on a phone keypad — for example, 1-800-FLOWERS is 1-800-3569377. Convert the letters to their corresponding digits before entering the fax number into the gateway.

Do I need to include a cover page?

Most fax-to-email services add a basic cover page automatically, showing your fax number, the recipient's fax number, and the time sent. You can usually turn this off in your account settings if you prefer. If you want a custom cover page, create it as a separate document and attach it as the first file, or include it in a multi-page PDF.

How long does it take for a fax to arrive?

Most faxes arrive within five to ten minutes. The gateway needs a minute or two to convert your email, then a few minutes to dial and transmit depending on document length and connection speed. You'll receive a confirmation email once delivery is complete, so you'll know exactly when it went through.

Can I send a fax from my phone?

Yes. Open your phone's email app, compose an email to the fax gateway address, attach a photo or PDF of your document, and send it. The process is identical to sending from a computer. Some fax services also offer a mobile app that may be slightly faster, but email works just as well.