how to retrieve email address from a line?

I have a file that contains one or more email addresses in every line as shown below: -- file.txt -- the 1st line email address first@domain1.com first line ends. the 2nd line email address (second@domain2.com) 2nd line ends. the 3rd line email address "third@domain3.com" 3rd line ends the 4th line email address blah@domain14.com and boo@domain5.com the last line last@domain6.com. <-- YES a "." follows the email!! --------------- How do I retrieve the email address from each line to the following format? -- output -- first@domain1.com second@domain2.com third@domain3.com blah@domain4.com boo@domain5.com last@domain6.com ------------ Thank you very much for your help!