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Home > Guides > Fax from Outlook
Yes, through an email-to-fax service: you send an email to a special gateway address and the service converts your attachment into a fax. Outlook itself has no built-in fax sending, on desktop or web. Here is how the gateway format works, why many workplaces block it, and a simpler option.
| Email part | What it becomes |
|---|---|
| To field | The destination fax number plus the provider's domain, for example 14165550134@faxprovider.example. This format is what tells the service to send a fax instead of an email. |
| Subject line | Usually becomes the cover page, or is ignored. Check your provider's rules before relying on it. |
| Attachment | The actual fax. PDF is the safest choice; most providers also accept common image and office formats. |
| Body text | Often dropped entirely. Do not put anything important only in the body. |
It used to, sort of. Very old versions of Outlook on Windows could hand a document to Windows' own fax feature, but that feature needs a physical phone line and a fax modem attached to your computer, which almost nobody has anymore. Microsoft never rebuilt it for the cloud era. The "Fax" fields you see on Outlook contacts are just address-book metadata: typing a number there labels it, it does not give Outlook the ability to dial it.
So the email-to-fax trick is a workaround: Outlook sends a normal email, and a third-party gateway sitting on a real phone network converts it. You are not really faxing from Outlook; you are emailing a robot that faxes for you.
If your company runs on Microsoft 365, the gateway address may simply bounce. Mail admins can restrict which external domains users may email, and fax-gateway domains are a common casualty of data-loss-prevention policies: the whole point of email-to-fax is moving documents off the email system and onto the phone network, which is exactly the kind of thing a compliance team wants to control.
There is a second, subtler problem. Email was never designed for delivery confirmation, and the gateway's "fax sent" receipt is only as trustworthy as the provider. If you need real proof that a fax reached its destination, a service that gives you an actual transmission report beats an email receipt every time.
Only if the provider gave you a fax number first, which makes it a different product (a hosted fax number with email delivery). Sending a fax to an email address is not a thing on the public phone network: the receiving side has to be a fax number somewhere. Keep this straight before you sign up for anything, because "email to fax" and "fax to email" are sold separately.
Yes. LetterAgent is currently in testing for fax: you describe the fax to your AI assistant, the assistant gives you a per-fax quote with the page count verified, you approve the exact total, and you pay once through Stripe. Then it is sent. No gateway addresses to memorize, no admin to beg for domain allow-listing, and no modem.
Two honest limits: LetterAgent sends to US and Canadian fax numbers only, and it cannot receive faxes. If you need inbound faxing (a number people can fax back to), you need a hosted fax-number provider instead.
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