LetterAgent
Mail physical letters by just asking your AI assistant.
Home > Guides > Fax from a computer
Upload your document to an online fax service, enter the recipient's fax number, and the service dials out over the phone network on your behalf. No fax machine, no phone line, no special software: your computer only needs the file and a browser. The recipient's machine receives it as an ordinary fax, with no way to tell you never touched a phone line.
| Method | How it works | Best when |
|---|---|---|
| Online fax portal | Upload a PDF in the browser, type the fax number, send | One-off faxes from a desktop |
| Email to fax | Attach the document to an email addressed to the fax number at the provider's domain | You live in your inbox and want a paper trail |
| LetterAgent (in testing) | Ask your AI assistant, approve the quoted total, pay once through Stripe | You want the fax handled without signing up anywhere |
| Built-in OS faxing (older) | Windows Fax and Scan dialing through a modem | Mostly obsolete: requires a dial-up modem few computers still have |
PDF, always. Online fax services convert your upload into the fax image format (essentially a black-and-white picture of each page), and PDF converts cleanly. Word documents and image files usually work too, but they get rendered through an extra conversion step that can shift margins or fonts. Export to PDF first and you control exactly what the recipient sees.
Two formatting details matter more than people expect. Fax is black and white, so light gray text and pale highlights wash out entirely: use dark text on a white background. And the old fax standard is roughly 200 dots per inch, so tiny footnotes and fine print that look crisp on your screen can turn to mush. If a detail matters, make it bigger before you send.
Every online fax service returns a transmission report: sent, failed, or busy, with a timestamp. A successful report means the recipient's fax machine (or their own online fax service) answered and received the pages. It does not mean a human read it. That distinction matters for anything important: for a job application or a medical form, follow up by phone or email to confirm someone actually has it. Treat the transmission report like a delivery receipt, not a read receipt.
Failed sends usually come down to three causes: a wrong or disconnected number, a recipient machine that was busy or out of paper, or a file that failed conversion. Most services retry busy numbers automatically a few times. If it fails outright, double-check the number digit by digit: fax numbers are often printed on letterheads with extensions or pause codes that do not belong in the dial string.
A cover sheet is the first page of the fax and carries the recipient's name, your name and callback number, the page count, and a line about what the fax contains. It exists because fax machines sit in shared offices: the cover sheet is how the right person claims the pages from the output tray. For a one-page fax to someone's direct line you can skip it; for anything going to a main office number or a busy department, include one. It is the difference between your fax reaching a desk and reaching a recycling bin.
That is what LetterAgent's fax feature is for, and it is currently in testing: you describe the fax to your AI assistant, get a per-fax quote with the page count verified, approve the exact total, and pay once through Stripe. It handles US and Canadian fax numbers only, and there are no inbound faxes. Because fax is still in testing with activation in progress, treat it as available in testing rather than something to rely on for a deadline today. For anything time-critical, use an established online fax portal until the testing phase is complete.
Ready to fax it? Fax with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is sent.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com