Obambu

Obambu (https://obambu.com) is our new email server for domain immie.org.

Configuration

Dynamic aliases

• Dynamic aliases are setup as global email filters.
• Example:

• Filter name: Starts with mpe.
• Rules: Any recipient, matches regex.

^mip\..*@immie\.org$

• Action: Deliver to folder

/immie.org/mpe

• We can use a more complex regular expression to match all possible dynamic alias (doing so also kinda simplify debugging using Obambu test filter).

• It's important to use Any Recipient instead of To, so that the match is done on the email address, and not the complete To: header that might include some extra characters (like "ABC" <abc@xyz.com>).

• To only matches the address in To: (including the extra characters like name, < and >...).

• Issue — BCC mails are not redirected by the filter above.

• To debug, we can use Obambu test filter utility, feeding into it the complete mail we received on postmaster account.

Doing so, we see that some headers are ignored by the filter (including Envelope-to:).

• Our only solution so far is to do a filter Any header, matches regex, and a complex regex:

\n\tfor (mip\.|m\.|mpe\.|michael|peeters-ml1|hyper|fuujuhi).*@immie\.org;\n

• This matches a line in the following header:

Received: from ober.noekeon.org ([91.134.133.203]:56096)
	by cp5.obambu.com with esmtp (Exim 4.97.1)
	(envelope-from <michael.peeters@noekeon.org>)
	id 1svChR-00000001Dio-3hEG
	for mip.anything@immie.org;
	Mon, 30 Sep 2024 11:28:13 +0200

• However, this DOES NOT WORK if there are multiple Bcc recipient in the same domain. In that case the Received: header doesn't contain any address, and only Envelope-to: contains the list of multiple recipients:

Envelope-to: mip.anything@immie.org,
 mpe.anything@immie.org
Received: from ober.noekeon.org ([91.134.133.203]:37740)
	by cp5.obambu.com with esmtp (Exim 4.97.1)
	(envelope-from <michael.peeters@noekeon.org>)
	id 1svEn5-00000002MtP-0eUN;
	Mon, 30 Sep 2024 13:42:10 +0200

• Ideally, the Any Recipient should also match the header Envelope-to:.

Email migration

We use offlineimap to transfer mail from Gandi.net in a local Maildir, and then to Obambu server.

• offlineimap configuration (file ~/.offlineimaprc):

[general]
accounts = MpeGandi

#### MPE #################

[Account MpeGandi]
localrepository = LocalMpe
remoterepository = RemoteMpeGandi

[Account MpeObambu]
localrepository = LocalMpe
remoterepository = RemoteMpeObambu

[Repository LocalMpe]
type = Maildir
localfolders = ~/imap.noidx/mpe

[Repository RemoteMpeGandi]
type = IMAP
remotehost = mail.gandi.net
starttls = yes
ssl = no
sslcacertfile = /etc/ssl/certs/ca-certificates.crt
remoteport = 143
remoteuser = user@domain.org
remotepass = XXXXXXXXXXX
readonly = True

[Repository RemoteMpeObambu]
type = IMAP
remotehost = cp5.obambu.com
starttls = yes
ssl = yes
sslcacertfile = /etc/ssl/certs/ca-certificates.crt
remoteport = 993
remoteuser = user@domain.org
remotepass = XXXXXXXXXXXXXX
readonly = False

Before sending mails to obambu:

• Remove the Trash folder.
• Add INBOX. to all folders without such prefix.

This is mandatory because Obambu uses a different folder structure.

Tips

Send emails to test mail filters

This use sendmail from postfix:

#!/bin/bash

# Send the email
# We test both bare address and address with name ("ABC" <abc@xyz.com>).
send_mail()
{
    recipient=$1
    filter=$2

    echo recipient: $recipient / filter: $filter

    /usr/sbin/sendmail -t <<EOF
From: michael.peeters@noekeon.org
To: $recipient
Subject: Test email for filter: $filter

This is a test email to check that the filter
at server level works correctly.

If this mail shouldn't be sent to you, tell me ;-)

Test email for filter: $filter
EOF

    /usr/sbin/sendmail -t <<EOF
From: michael.peeters@noekeon.org
To: "Some Name Here" <$recipient>
Subject: Test email for filter: $filter

This is a test email to check that the filter
at server level works correctly.

If this mail shouldn't be sent to you, tell me ;-)

Test email for filter: $filter
EOF
}

prefix="mpe."; send_mail "${prefix}anything@immie.org" "starts with $prefix"
prefix="mip."; send_mail "${prefix}anything@immie.org" "starts with $prefix"