Is it possible to have multiple values under the same field in a .csv file?
I have an \"email\" field on my webpage, and the user may optionally type in multiple address
Yes. You can have multiple values in one filed of a CSV file.
If the multiple values are separated by space you need not do anything special but if the values are separated by a comma, you need to enclose the entire field in double quotes.
Example:
Name,E-mail
foo,foo@a.com foo foo@b.com
bar,"bar@a.com,bar@b.com"