Improve support for subaddressing

[CodeZombieCH]

Support for subaddressing is currently very limited.

Example: john.doe+tag@example.com

Considering the example above, the current implementation would simply remove the tag from the recipient address and use the changed address to lookup the appropriate mapping.

Proposal

• Consider support subaddressing on mapping level instead of a global option
• Support different type of characters (plus, hyphen, ...)

Configuration

Pass-through subaddressing

"forwardMapping": {
    "+@your-domain.tld": [
        "forwarder+<tag>@some-other-domain.tld",
        "john.doe+forwarder@some-other-domain.tld"
    ]
}

Example:

recipient@your-domain.tld => forwarder@some-other-domain.tld
recipient@your-domain.tld => john.doe+forwarder@some-other-domain.tld
recipient+foo@your-domain.tld => forwarder+foo@some-other-domain.tld
recipient+foo@your-domain.tld => john.doe+forwarder@some-other-domain.tld

Strip subaddressing

"forwardMapping": {
    "+@your-domain.tld": [
        "forwarder@some-other-domain.tld",
        "john.doe+forwarder@some-other-domain.tld"
    ]
}

Example:

recipient@your-domain.tld => forwarder@some-other-domain.tld
recipient@your-domain.tld => john.doe+forwarder@some-other-domain.tld
recipient+foo@your-domain.tld => forwarder@some-other-domain.tld
recipient+foo@your-domain.tld => john.doe+forwarder@some-other-domain.tld

Disabled subaddressing

"forwardMapping": {
    "@your-domain.tld": [
        "forwarder@some-other-domain.tld"
        "john.doe+forwarder@some-other-domain.tld"
    ]
}

Example:

recipient@your-domain.tld => forwarder@some-other-domain.tld
recipient@your-domain.tld => john.doe+forwarder@some-other-domain.tld
recipient+foo@your-domain.tld => *no mapping*