It's really not possible to

kazimmerman — Sun, 06 Apr 2014 16:14:15 +0000

It's really not possible to define a regular expression to extract a string without knowing the pattern that you are looking for. For example, in this case you don't need a regular expression. Just look for the string between "@" and "?". However, there must be more extreme cases that are possible if this doesn't work for you. So, you need to specify moreso what the pattern is you know will exist and what portion you want to get back. This can either be a literal pattern, like "mailto:{word}@{string I want}?{more}", or you could at least start with more examples of the type of strings you want to extract a component from, like:

mailto:info@abc.com?subject=Feedback
mailto:somethingelse@a.b.org?word=AnotherThing
mailto:thiscanhavenumb3rsands!mbols@url.co.uk

If you can provide more information, we can get closer to the regular expression that works for you.