REGEX - Pattern for email and doesn't allow double dashes

Question

I've the following email pattern:

(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)

Now I have two questions:

1. Additionally I don't want to allow double dashes e.g.:

   not allowed: john--doe@x--x.c--om

2. What do you think about the pattern, could it be simplified or does it have some mistakes or uncovered strings?

Answer 1

You can use this regex: (?!.*?--)(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$). I added a negative lookahead that will stop the match if followed by .*--, if it contains --

If you want to use this for a website then you should use another regex as suggested in a comment to match email adresses more strictly, or use available functions in language.