using System;
using System.Linq;
using System.Collections.Generic;
using System.Text.RegularExpressions;
public class Test
{
	public static void Main()
	{
		 var strs = new List<string> {"abcd@efg.com this is just some text. these are just some numbers 123456 xyz@xyz.com asdasd asdad",
"abcd@efg.com mnop@qrs.com This is just some text. these are just some numbers 123456 xyz@xyz.com asdasd asd",
"abcd@efg.com mnop@qrs.com uvw@xyz.com This is just some text. these are just some numbers 123456 xyz@xyz.com asdad" };
		 foreach (var s in strs) 
		 {
		 	var results = Regex.Matches(s, @"(?i)\G\s*([A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,6})")
		 		.Cast<Match>()
		 		.Select(x => x.Groups[1].Value);
			Console.WriteLine(string.Join(", ", results));
		 }
 
	}
}

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