When then email comes in, the first thing that you have to do is to save the attached drawing(s) to your hard disk. To do that, just right click on the attachment and choose Save As. Then select your destination, eg, your desktop, and then click save. Now that the file is on your desktop we can open it from ACAD. Start ACAD and then go to File->Open and then choose the file on your desktop. Once open, you see the Model layout. Depending on the drawing, there might be some more layouts created by the draughtsman. These can be selected by the tabs at the bottom of the page labelled 'Model', 'Layout1' 'Layout2' etc. Choose the appropriate tab and then go to File and Plot/Print.
You are now in the plotting dialog box. There are two tabs. Plot Device and Plot Settings. Go to the Plot Device Tab. In here your default printer should already be selected, if it is not the printer you want, pull down the list and select your plotter. Now go to the Plot Settings tab, and in here we can set our printing options. First off, choose your paper size, eg, A1, once you have done that, choose either Portrait or Landscape depending on the drawing. Next you want to select the plot area. This is what part of the drawing you want to print. If you were in a layout tab that has the full view of the drawing and any title blocks put in that space, you can choose Layout, and this will print exactly what you see on the Layout Tab. If you are in Model (space) tab you can choose 'Window', this will allow you to manually select the area of the drawing you want to print. You can also choose Extents, which will plot the extents of the entire drawing, or else Display, which will print the displayed area of the drawing that is on your screen. I would recommend choosing Extents for a Model Space drawing or Layout for Layout tabs and for specific areas of the drawing choose Window.
You then have the option of scaling, if you want to print to an A1 sheet, and the drawing is drawn to scale on an A1 sheet, then you would not need to scale the drawing and leave the scale at 1:1. If you want to change the drawing to fit the page, you can select Scaled To Fit and select the page size you want. Once you have done all this you can then select a print preview, do this by pressing Full Preview on the bottom of the print dialog box.
If this is ok you can Right Click on the previewed drawing and select Plot, and it will send the drawing to the plotter, if you wish to make some more changes, like change from Landscape to Portrait, right click on the drawing and select Exit, this will return you to the Printing Dialog Box, and from there once you make your change you can either press OK to print, or do another print preview to make sure it is ok.