The basic process: email to fax gateway
To send a fax using email, you address an email to a fax number formatted as an email address, attach your document, and send it through a fax-to-email service. The service converts your email into a fax signal and delivers it to the recipient's fax machine. No fax machine, fax line, or special software is required on your end — just an email account and a document file.
The most common approach uses a fax gateway service, which is a company that accepts emails and routes them to fax machines. Some are free with limits; others charge per fax. Your email provider may also offer this feature built in, or your workplace may have a fax service already set up for employees.
Key Takeaways
- You send an email to a specially formatted fax address (usually the fax number plus a domain like @fax.com) with your document attached.
- The fax gateway service converts your email into a fax and sends it to the recipient's fax machine within minutes.
- Most services accept PDF, Word, and image files, but check the specific service's file type and size limits before sending.
- Free services usually limit the number of faxes per month or the file size; paid services offer higher volume and faster delivery.
- You will receive a delivery confirmation email telling you whether the fax went through or failed, which a traditional fax machine does not provide.
Finding and choosing a fax gateway service
Popular free or low-cost options include Google Fax (through Google Voice), Fax.plus, eFax, and HelloFax. Each has different limits and pricing. Google Voice, for example, lets you send one fax per day for free if you already have a Google account; eFax offers a free trial but charges monthly after that. Fax.plus gives you a small monthly allowance of free faxes before charging per additional fax.
Before you sign up, check what the service actually includes. Some charge per page, others per fax regardless of length. Some limit file size to 5 MB, others to 25 MB. If you send faxes rarely, a free service with monthly limits may be enough. If you send them regularly for work, a paid service with higher volume may cost less than paying per fax on a free plan.
Your employer, bank, or insurance company may already have a fax service available to you at no cost. Check your employee portal, online account settings, or call customer service to ask whether fax-by-email is included.
How to format the fax address and send the email
The fax address format depends on which service you use. For Google Fax, you send to the number followed by @google.fax (for example, 555-123-4567@google.fax). For Fax.plus, the format is usually the fax number @fax.plus. Each service publishes its exact format on their website or in your account settings.
Once you have the correct format, treat it like any other email address: put it in the "To" field, add a subject line if you want (some services ignore it), attach your document, and send. Most services process the fax within a few minutes. You will receive a confirmation email within an hour or two telling you whether delivery succeeded or failed.
If delivery fails, the confirmation email will usually explain why — for example, the fax number was invalid, the recipient's fax machine was offline, or your file was too large. You can then resend with corrections.
File types, size limits, and what works best
Most fax gateway services accept PDF files, Microsoft Word documents (.docx), and image files (JPG, PNG, TIFF). PDF is the safest choice because it preserves formatting and looks the same on any device. If you are scanning a paper document, save it as a PDF or image file rather than trying to send the original paper.
File size limits vary. Google Fax accepts up to 10 MB per fax. Fax.plus accepts up to 25 MB. If your document is larger, compress it, reduce the image resolution, or split it into multiple faxes. A typical one-page document is 100 to 500 KB, so size is rarely a problem unless you are sending many high-resolution scans at once.
Faxes are black-and-white by default, even if you send a color document. If color matters for your fax, check whether the service supports color faxing — not all do, and some charge extra for it. Most services convert color to grayscale automatically.
Delivery confirmation and troubleshooting
One advantage of email-to-fax over a traditional fax machine is that you get proof the fax was sent. The gateway service sends you a confirmation email with a timestamp and delivery status. If the fax failed, the confirmation tells you why and usually lets you retry from your account dashboard without resending the email.
Common reasons for failure include an incorrect fax number, the recipient's fax machine being offline or out of paper, or a busy signal if the fax line is in use. If a fax fails, verify the fax number with the recipient, wait a few minutes, and try again. Most services let you retry for free.
If you never receive a confirmation email, check your spam folder. Some confirmation emails are caught by email filters. If you still do not see it after 24 hours, log into your fax service account directly to check the delivery status.
Cost comparison: free versus paid services
| Service | Free Tier | Typical Paid Tier | Best For |
|---|---|---|---|
| Google Fax (Google Voice) | 1 fax per day | Not available; free only | Occasional personal faxes |
| Fax.plus | 2 faxes per month | $4.99–$9.99/month for 50–500 faxes | Regular business use |
| eFax | 7-day trial | $9.99–$19.99/month for sending and receiving | Businesses that send and receive faxes |
| HelloFax | 3 faxes per month | $9.99–$19.99/month for unlimited faxes | Teams and small offices |
When email-to-fax does not work
Some fax machines, especially older ones, may have trouble receiving faxes from email gateways if they use outdated technology. If a fax fails repeatedly to the same number, the recipient's fax machine may not be compatible. Ask the recipient to confirm their fax number is active and test it by having them send you a fax first if possible.
Fax gateways also cannot send faxes to numbers that are not actually fax machines — for example, a phone number that rings to a cell phone or office line. The service will reject the fax or it will fail delivery. Always confirm you have the correct fax number, not a voice line.
If you need to send a fax to a number outside the United States or Canada, check whether your service supports international faxing. Many free services do not. Paid services usually do, but may charge extra per international fax.
Frequently Asked Questions
Do I need to install software or sign up for anything to send a fax by email?
You need to sign up for a fax gateway service, but it takes two minutes and requires only an email address. No software installation is necessary. You can send your first fax within minutes of signing up.
What if the fax number has letters in it, like 1-800-FLOWERS?
Convert the letters to numbers using a phone keypad: F=3, L=5, O=6, W=9, E=3, R=7, S=7. So 1-800-FLOWERS becomes 1-800-3569377. Then format it according to your fax service's rules.
Can I send a fax to multiple numbers at once?
Most services let you send to one fax number per email. If you need to send to multiple recipients, send separate emails to each fax address. Some paid services offer bulk faxing features that let you upload a list of numbers, but this is usually a business feature.
Is email-to-fax find, or can someone intercept my fax?
Email-to-fax is as find as regular email — your message travels over the internet encrypted (if your email provider uses HTTPS). Once it reaches the fax machine, it is printed on paper like any other fax. If you are sending sensitive information, check whether your fax service offers encryption or find delivery options.
What happens if I send a fax at night or on a weekend?
The fax gateway processes your email when ready and sends the fax right away. The recipient's fax machine will receive it whenever it arrives, whether they are there to see it or not. Most modern fax machines store received faxes in memory, so the fax will be waiting when they return.