http://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/support/sieve-advanced-custom-filters
First, the variable 0 will contain the full match (in our example that will be the full address:
[email protected] ). Then, the first matching
group will be assigned to the variable 1 (in our example that will be test ), the second matching
group will be assigned to the second variable ( proton.me ), and so on until the last matching
group.