The advanced telephone handset - priced at £79.99 ($127) will be equipped with a miniature screen, comes with voice mail, fax and an electronic note pad to store telephone numbers and email addresses.
Only one in five UK households have e-mail access and the two firms believe that their product will change all that.
Amstrad hopes that the e-m@iler will repeat the success the company had in the late 1980s with its line of cheap personal computers.
The advanced telephone handset - priced at £79.99 ($127) will be equipped with a miniature screen, comes with voice mail, fax and an electronic note pad to store telephone numbers and email addresses.
Share drop
The mystery over what kind of internet device Amstrad would launch had strongly boosted the firm's share price by more than 600%, from 83 pence at the end of September 1999 to 607 pence at the end of trading on Tuesday.
However, disappointment over the fact that the e-m@iler will not allow consumers to actually surf the internet made many investors to reconsider Amstrad's stock market valuation.
The firm's share price plunged by as much as 14% before recovering slightly.
Subsidised price
The look of the e-m@iler is still under wraps and will be revealed later on Wednesday.
While Amstrad provides the hardware, BT will run the e-mail service.
The relatively low price of the e-m@ilers is made possible because Amstrad plans to sell them below cost. The company hopes to make up the shortfall by receiving a share of the revenues generated by e-mail phone calls.
The success of mobile phones was built on a similar cost model.
Consumers taking up the service may have to brace themselves for a flood of adverts, though. Amstrad says it hopes for additional revenues from sending ads to users.
It took the two firms 18 months to develop the service.