---
name: "public-inbox-pop3d"
section: "1"
platform: "linux"
package: "public-inbox"
version: "1.9.0-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/public-inbox-pop3d"
---

# public-inbox-pop3d(1)

POP3 server for sharing public-inboxes

## NAME

public-inbox-pop3d - POP3 server for sharing public-inboxes

## SYNOPSIS

```
  public-inbox-pop3d [OPTIONS]
```

## DESCRIPTION

public-inbox-pop3d provides a POP3 daemon for public-inbox. It uses options and environment variables common to all read-only [**public-inbox-daemon**(8)](/public-inbox-daemon/8.md) implementations, but requires additional read-write storage to keep track of deleted messages on a per-user basis.

Like [**public-inbox-imapd**(1)](/public-inbox-imapd/1.md), `"public-inbox-pop3d"` will never require write access to the directory where the public-inboxes are stored.

It is designed for anonymous access, thus the password is always `"anonymous"` (all lower-case).

Usernames are of the format:

```
        C<$UUID@$NEWSGROUP_NAME>
```

Where `$UUID` is the output of the [**uuidgen**(1)](/uuidgen/1.md) command.  Dash (`"-"`) characters in UUIDs are ignored, and `"[A-F]"` hex characters are case-insensitive.  Users should keep their UUIDs private to prevent others from deleting unretrieved messages. Users may switch to a new UUID at any time to retrieve previously-retrieved messages.

Historical slices of 50K messages are available by suffixing the integer `$SLICE`, where `0` is the oldest.

```
        C<$UUID@$NEWSGROUP_NAME.$SLICE>
```

It may be run as a different user than the user running [**public-inbox-watch**(1)](/public-inbox-watch/1.md), [**public-inbox-mda**(1)](/public-inbox-mda/1.md), or [**public-inbox-fetch**(1)](/public-inbox-fetch/1.md).

To save storage, "publicinbox.pop3state" only stores the highest-numbered deleted message

## OPTIONS

See common options in "OPTIONS" in [**public-inbox-daemon**(8)](/public-inbox-daemon/8.md).

- \-l PROTOCOL://ADDRESS/?cert=/path/to/cert,key=/path/to/key

  - \--listen PROTOCOL://ADDRESS/?cert=/path/to/cert,key=/path/to/key

  In addition to the normal `"-l"`/`"--listen"` switch described in [**public-inbox-daemon**(8)](/public-inbox-daemon/8.md), the `"PROTOCOL"` prefix (e.g. `"pop3://"` or `"pop3s://"`) may be specified to force a given protocol.

  For STARTTLS and POP3S support, the `"cert"` and `"key"` may be specified on a per-listener basis after a `"?"` character and separated by `","`. These directives are per-directive, and it's possible to use a different cert for every listener.

- \--cert /path/to/cert

  The default TLS certificate for optional STARTTLS and POP3S support if the `"cert"` option is not given with `"--listen"`.

  If using systemd-compatible socket activation and a TCP listener on port 995 is inherited, it is automatically POP3S when this option is given. When a listener on port 110 is inherited and this option is given, it automatically gets STARTTLS support.

- \--key /path/to/key

  The default private TLS certificate key for optional STARTTLS and POP3S support if the `"key"` option is not given with `"--listen"`.  The private key may be concatenated into the path used by `"--cert"`, in which case this option is not needed.

## CONFIGURATION

Aside from `"publicinbox.pop3state"`, `"public-inbox-pop3d"` uses the same configuration knobs as [**public-inbox-nntpd**(1)](/public-inbox-nntpd/1.md), see [**public-inbox-nntpd**(1)](/public-inbox-nntpd/1.md) and [**public-inbox-config**(5)](/public-inbox-config/5.md).

- publicInbox.pop3state

  A directory containing per-user/mailbox account information; must be writable to the `"public-inbox-pop3d"` process.

- publicInbox.\<name\>.newsgroup

  The newsgroup name maps to a POP3 folder name.

## CONTACT

Feedback welcome via plain-text mail to \<mailto:meta@public-inbox.org\>

The mail archives are hosted at \<https://public-inbox.org/meta/\>, and \<nntp://news.public-inbox.org/inbox.comp.mail.public-inbox.meta\>, \<nntp://4uok3hntl7oi7b4uf4rtfwefqeexfzil2w6kgk2jn5z2f764irre7byd.onion/inbox.comp.mail.public-inbox.meta\>

## COPYRIGHT

Copyright all contributors \<mailto:meta@public-inbox.org\>

License: AGPL-3.0+ \<https://www.gnu.org/licenses/agpl-3.0.txt\>

## SEE ALSO

[**git**(1)](/git/1.md), [**git-config**(1)](/git-config/1.md), [**public-inbox-daemon**(8)](/public-inbox-daemon/8.md), [**public-inbox-config**(5)](/public-inbox-config/5.md), [**public-inbox-nntpd**(1)](/public-inbox-nntpd/1.md), [**uuidgen**(1)](/uuidgen/1.md)