Open your form in DESIGN mode and click on the combo box. If your properties window isn't open, click VIEW / PROPERTIES on the menu bar.
Next, click on the DATA tab in the properties window. The rowsource should be about the 4th item down. If you click just to the right of the rowsource property (in the gray area that is just to right of the white spot) a button with 3 dots (an elipsis) will appear. Click that button to open up what you normally see when creating a query.
Add the correct table by either selecting the table name from the dialog box that appears and clicking the ADD button, or double-clicking on the table name. Select the fields that you want to be in the combo box. You will probably select the person's name and also their email address. Then close the query and say YES when asked if you wish to "Save changes to the SQL statement and update the property."
Next, set the BOUND COLUMN (the property just below the rowsource one) to the number of the column in the query you just created that has the email address. Next, click on the FORMAT tab of the properties window. The third one down should be COLUMN COUNT. Set that to the number of fields that you put into your query (2, if you chose name and email address).
Next, two properties down the list will be COLUMN WIDTHS. Set those to the widths (in inches) that you want to see in your combo box. You may want to view both columns or you may just want to show the person's name and hide their email address.
To show only the name and not the email address, set the column you don't want to see to 0" and the one you do to something like 2"
If you had selected the names column first and the email address 2nd in your query, and wanted to hide the email address, the setting in the COLUMN WIDTH property would be something like 2";0"
