Mail::MIMEDefang(3)

📦
version 3.7.1 · 11 versions
, in fedora 43, fedora 44

💖 Mail::MIMEDefang 💖

okay bestie, sit down, hydrate, because we're talking about Mail::MIMEDefang — the email filtering milter. yep, that's the whole name, no notes. this is the Mail::MIMEDefang(3) manual page and i'm about to make it make sense, fr fr. 🦋

✨ NAME ✨

Mail::MIMEDefang — email filtering milter. that's it. that's the name. iconic. 👑

🌸 DESCRIPTION 🌸

Mail::MIMEDefang is a whole framework for filtering e-mail. the way it works: it uses Sendmail's "Milter" API, plus some C glue code, plus some Perl code, and together they let you write high-performance mail filters in Perl. no cap. 🔥

so like, why do people even use MIMEDefang? bestie, let me list:

  • Block viruses 🦠
  • Block or tag spam
  • Remove HTML mail parts
  • Add boilerplate disclaimers to outgoing mail
  • Remove or alter attachments
  • Replace attachments with URL's
  • Implement sophisticated access controls.

and honestly? you're limited only by your imagination. if you can think of it and code it in Perl, you can do it with MIMEDefang. periodt. 💅

🎀 METHODS 🎀

init_globals

Initialize global variables used across MIMEDefang instance and filter. housekeeping first, always. 🧹

print_and_flush(text)

Prints to stdout and flush buffer. say it out loud and don't hold it in. 🗣️

md_openlog(tag, facility)

Initialize e syslog object using Sys::Syslog or Unix::Syslog as appropriate. whichever one fits, it picks. ✨

md_syslog(facility, msg)

Prints a message to syslog(3) using the specified facility.

md_graphdefang_log

This is called to log events that occur during mimedefang processing. It should be called from mimedefang-filter with appropriate event names and values.

Possible examples:

md_graphdefang_log('virus',$VirusName,$filename);
md_graphdefang_log('spam',$hits);
md_graphdefang_log('bad_filename',$filename,$extension);

If you need to log UTF-8 strings you can call the sub as:

md_graphdefang_log('spam',$hits, undef, 1);

md_graphdefang_log_array

This is called to log events that occur during mimedefang processing. It should be called from mimedefang-filter with appropriate event names and values.

Possible examples:

md_graphdefang_log_array('virus',0,\@info);

If you need to log UTF-8 strings you can call the sub as:

md_graphdefang_log_array('spam',1,\@info);

detect_and_load_perl_modules

Automatically detect and load Perl modules needed for some features like SpamAssassin, rbl checks, zip file listing and HTML parsing. it does the homework for you, love that. 📚

detect_antivirus_support

Check if antivirus support should be loaded by looking at %Features.

init_status_tag

Open the status file descriptor.

set_status_tag(depth, tag)

Sets the status tag for this worker inside the multiplexor.

push_status_tag(tag)

Updates status tag inside multiplexor and pushes onto stack.

pop_status_tag

Pops previous status of stack and sets tag in multiplexor.

percent_encode(str)

Encode a string with unsafe chars as "%XY" where X and Y are hex digits.

percent_encode_for_graphdefang(str)

Encode a string with unsafe chars as "%XY" where X and Y are hex digits.

Quotes or spaces are not encoded but commas are encoded. yes, it's picky like that. 🙈

percent_decode(str)

Decode a string previously encoded by percent_encode().

write_result_line ( $cmd, @args )

Writes a result line to the RESULTS file.

$cmd should be a one-letter command for the RESULTS file.

@args are the arguments for $cmd, if any. They will be percent_encode()'ed before being written to the file.

Returns 0 or 1 and an optional warning message.

signal_unchanged

Tells mimedefang C program message has not been altered. untouched, unbothered. ✋

signal_changed

Tells mimedefang C program message has been altered. glow up confirmed. 💫

in_message_context(name)

Returns 1 if we are processing a message; 0 otherwise.

in_filter_wrapup(name)

Returns 1 if we are not in filter wrapup; 0 otherwise.

in_filter_context

Returns 1 if we are inside filter or filter_multipart, 0 otherwise.

in_filter_end(name)

Returns 1 if we are inside filter_end 0 otherwise.

send_quarantine_notifications

Sends quarantine notification message, if anything was quarantined. snitches get... notifications. 📬

signal_complete

Tells mimedefang C program Perl filter has finished successfully.

Also mails any quarantine notifications and sender notifications.

send_mail(fromAddr, fromFull, recipient, body, deliverymode)

Sends a mail message using Sendmail.

Invokes Sendmail without involving the shell, so that shell metacharacters won't cause security problems. very demure, very safe. 🫶

Delivery mode parameter is the optional sendmail delivery mode arg (default "-odd").

send_multipart_mail(fromAddr, fromName, recipient, subject, body_text, body_html, extra_headers)

Sends a multipart mail message using Sendmail.

Invokes Sendmail without involving the shell, so that shell metacharacters won't cause security problems.

send_admin_mail(subject, body)

Sends a mail message to the administrator. hi admin bestie 👋

read_commands_file()

This function should only be called from "filter_sender" and "filter_recipient". This will read the "COMMANDS" file (as described in mimedefang-protocol(7)), and will fill or update the following global variables: $Sender, @Recipients, %RecipientMailers, $RelayAddr, $RealRelayAddr, $RelayHostname, $RealRelayHostname, $QueueID, $Helo, %SendmailMacros.

If you do not call "read_commands_file", then the only information available in "filter_sender" and "filter_recipient" is that which is passed as an argument to the function. so like, call it, or work with crumbs. your choice. 😭

🌈 SEE ALSO 🌈

and that's the whole page bestie, we ate and left no crumbs 🍓. this was version 3.7.1 from 2026-07-20, filed under Mail::MIMEDefang(3). go filter some mail, you got this 💜🦋✨

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