Basic findstr question

findstr is a simple string search function, and you can't really do anything complex with it.

For more complex string extraction, you probably need a regular expression

iRules 101 - #10 - Regular Expressions

However, be aware that using a regex is computationally expensive.

If your URL is /test?user=5555555@my.domain.com&pass=.....

user=(.*@([\w*\.]*))(\&|\#|$)

Then from the above regex, the Group 1 match is 5555555@my.domain.com

You can be more selective about what you terminate on.

To play with regex, go to regex101.com