Can I send an email to a fax number?

Question

Since I don't know the email address of the person I want to contact, but do have a fax number, can I compose an email in Thunderbird and send it to the fax number? Do I need an add-on or special format in 'send to'?

Answer 1

In general, a message sent to a fax machine requires a phone call, and email clients don't know how how to make phone calls.
Some years ago, it was quite common for ISPs to offer a limited number of free calls, usually SMS messages to mobiles, occasionally faxes IIRC. Most of these promotional services seem to have quietly vanished.
There used to be a network (TPC rings a bell) that ran a system where you could email to a fax server near to your destination, and they'd do the final mile, the fax call, for you, for free, but it always arrived with advertising added in.
So, all in all, it's not trivial to send a fax from an email client.
There are still businesses that do this, almost always for a fee. It's usually a two-way deal; you get a number to which others can send faxes, which end up in your email Inbox, and you can use the same number to send faxes by email.
Here's one I've used in the past.
http://home.efax.com/
This is '''not''' a recommendation.
Not so long ago, we all had a modem built into our computers. This, when connected up to a regular landline, with the relevant software, can allow your computer to work as a fax machine. Obviously, each fax you send costs you a phone call just as running a real fax machine would. Certainly, in Windows XP, the ability to send a fax was built in; you compose in a word processor or text editor, then select the fax device as the printer. A dialogue box would prompt you for the fax number to send it to. For all I know, this capability is still present in Windows 7 and 8.
If you don't have a landline, your mobile phone may offer something similar.