---
name: "Mail::Milter::Wrapper::DecodeSRS"
section: "3pm"
platform: "linux"
package: "libmail-milter-perl"
version: "0.07-2"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/Mail::Milter::Wrapper::DecodeSRS"
---

# Mail::Milter::Wrapper::DecodeSRS(3pm)

milter wrapper to decode SRS-encoded return path

## NAME

Mail::Milter::Wrapper::DecodeSRS - milter wrapper to decode SRS-encoded return path

## SYNOPSIS

```
    use Mail::Milter::Wrapper::DecodeSRS;
    my $milter = ...;
    my $wrapper = new Mail::Milter::Wrapper::DecodeSRS($milter);
    my $wrapper2 = &DecodeSRS($milter); # convenience
```

## DESCRIPTION

Mail::Milter::Wrapper::DecodeSRS is a convenience milter wrapper which  decodes MAIL FROM: return paths which have been encoded by the Sender  Rewrite Scheme, SRS.  (More information:  http://www.libsrs2.org/) This wrapper internally understands both the SRS0 and SRS1 encoding  schemes documented by the Mail::SRS author.

The decoded address is made available to the contained milter via the  `"envfrom"` callback, in the same way that a raw address would.

NOTE:  If the address is not SRS encoded, the contained milter is NOT  called for the duration of the message; instead, SMFIS\_ACCEPT is returned.  This is because the milter writer is expected to use this wrapper in a  chain that also includes the contained milter without wrapping, in order  to prevent a malicious sender from using SRS to bypass access checks.

For instance, the following is a proper usage of this wrapper in a chain:

```
    my $envfrommilter = ...;
    my $combinedmilter = new Mail::Milter::Chain(
        new Mail::Milter::Wrapper::UnwrapSRS($envfrommilter),
        $envfrommilter
    );
```

This behavior can also be used if, e.g., the MTA already does one form of  MAIL FROM: check, and the contained milter repeats that same database  check against SRS rewritten addresses.  (A good example would be a milter  emulating Sendmail's access\_db map.)

## AUTHOR

Todd Vierling, \<tv@duh.org\> \<tv@pobox.com\>

## SEE ALSO

Mail::Milter::Wrapper