How to store list<String> values in mail

I want to put all values of list containing id’s into a mail body but not able to do it.
Please help me?

@arpit.s6,

Could you explain a bit in details and provide an example?

maybe you want to concat the values
String.Join(",", YourListVar)

in case of each value should be on one line:
String.Join(Environment.NewLine, YourListVar)