Finding target site webmail address

hi guys, i am looking for a source that finds target site webmail addresses for free. can you help me with this? i am looking for codes and programs

Hello,
Use search (google...) dorks;
Mail in text site:

site:targetsite.com intext:"@targetsite.com"

Click to expand...

Webmail:

site:targetsite.com intext:"roundcube"

Click to expand...

If you want to do it with the tool, you can use the dorkscanner tools on github. Most webmail addresses are indexed by Google.