Skip to content

Add separate HELO SPF check with helo_check config option #172

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
notbrokenjemma merged 4 commits into from
Mar 19, 2026
Merged

Add separate HELO SPF check with helo_check config option #172

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
9c5cc4b
Add separate HELO SPF check with helo_check config option
fkoyer Mar 15, 2026
7757cd1
Retain existing behavior by default
fkoyer Mar 16, 2026
7278cde
Remove .claude
fkoyer Mar 16, 2026
0cd1f49
Fix existing behavior
fkoyer Mar 18, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
56 changes: 53 additions & 3 deletions lib/Mail/Milter/Authentication/Handler/SPF.pm
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ sub default_config {
'hide_none' => 0,
'best_guess' => 0,
'spfu_detection' => 0,
'helo_check' => 0,
};
}

Expand Down Expand Up @@ -85,7 +86,9 @@ sub envfrom_callback {
$self->{'spfu_chain'} = [];
}
delete $self->{'spf_header'};
delete $self->{'spf_helo_header'};
delete $self->{'spf_metric'};
delete $self->{'spf_helo_metric'};

my $spf_server = $self->get_object('spf_server');
if ( ! $spf_server ) {
Expand Down Expand Up @@ -174,8 +177,19 @@ sub envfrom_callback {
if ( $auth_domain ) {
$header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'policy.authdomain' )->safe_set_value( $auth_domain ) );
}
$header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'smtp.mailfrom' )->safe_set_value( $self->get_address_from( $env_from ) ) );
$header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'smtp.helo' )->safe_set_value( $self->{ 'helo_name' } ) );
if ( $config->{'helo_check'} ) {
# Add single property for this scope
if ( $scope eq 'mfrom' ) {
$header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'smtp.mailfrom' )->safe_set_value( $self->get_address_from( $env_from ) ) );
}
else {
$header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'smtp.helo' )->safe_set_value( $self->{ 'helo_name' } ) );
}
} else {
# Add properties for both scopes
$header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'smtp.mailfrom' )->safe_set_value( $self->get_address_from( $env_from ) ) );
$header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'smtp.helo' )->safe_set_value( $self->{ 'helo_name' } ) );
}
if ( !( $config->{'hide_none'} && $result_code eq 'none' ) ) {
$self->{'spf_header'} = $header;
}
Expand All @@ -199,6 +213,32 @@ sub envfrom_callback {
$self->dbgout( 'SPFHeader', $result_header, LOG_DEBUG );
}
}

# Separate HELO SPF check (only when the primary check was mfrom)
if ( $config->{'helo_check'} && $scope eq 'mfrom' ) {
eval {
my $helo_spf_request = Mail::SPF::Request->new(
'versions' => [1],
'scope' => 'helo',
'identity' => $self->{'helo_name'},
'ip_address' => $self->ip_address(),
'helo_identity' => $self->{'helo_name'},
);
my $helo_spf_result = $spf_server->process($helo_spf_request);
my $helo_result_code = $helo_spf_result->code();
$self->{'spf_helo_metric'} = $helo_result_code;
my $helo_header = Mail::AuthenticationResults::Header::Entry->new()->set_key( 'spf' )->safe_set_value( $helo_result_code );
$helo_header->add_child( Mail::AuthenticationResults::Header::SubEntry->new()->set_key( 'smtp.helo' )->safe_set_value( $self->{'helo_name'} ) );
if ( !( $config->{'hide_none'} && $helo_result_code eq 'none' ) ) {
$self->{'spf_helo_header'} = $helo_header;
}
$self->dbgout( 'SPFHeloCode', $helo_result_code, LOG_DEBUG );
};
if ( my $helo_error = $@ ) {
$self->handle_exception( $helo_error );
$self->log_error( 'SPF HELO Error ' . $helo_error );
}
}
};
if ( my $error = $@ ) {
$self->handle_exception( $error );
Expand Down Expand Up @@ -244,7 +284,11 @@ sub eoh_callback {
$self->handle_exception( $@ );
$self->add_auth_header($self->{'spf_header'});
}
if ( $self->{'spf_helo_header'} ) {
$self->add_auth_header($self->{'spf_helo_header'});
}
$self->metric_count( 'spf_total', { 'result' => $self->{'spf_metric'} } ) if $self->{'spf_metric'};
$self->metric_count( 'spf_total', { 'result' => $self->{'spf_helo_metric'} } ) if $self->{'spf_helo_metric'};
}

sub spfu_checks {
Expand Down Expand Up @@ -359,7 +403,9 @@ sub close_callback {
delete $self->{'spfu_chain'};
delete $self->{'spfu_detected'};
delete $self->{'spf_header'};
delete $self->{'spf_helo_header'};
delete $self->{'spf_metric'};
delete $self->{'spf_helo_metric'};
delete $self->{'dmarc_domain'};
delete $self->{'dmarc_scope'};
delete $self->{'dmarc_result'};
Expand All @@ -385,9 +431,13 @@ Implements the SPF standard checks.
| if not hidden at all
"best_guess" : 0, | Fallback to Org domain for SPF checks
| if result is none.
"spfu_detection" : 0 | Add some mitigation for SPF upgrade attacks
"spfu_detection" : 0, | Add some mitigation for SPF upgrade attacks
| 0 = off (default)
| 1 = mitigate
| 2 = report only
"helo_check" : 0 | Perform a separate HELO SPF check in
| addition to the mfrom check
| 0 = off (default)
| 1 = on
},