Pop Connector what worked like in NS7 with RspamD etc

Feature
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Just a Question and i hope it is not annoying. Is there an idea to have the Pop3 Connector in NS8 like i had it in NS7? I know we have Imapsynch but from my point of view it is different to use and did not the same like the connector… Thanks in Advanced

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I’m sorry but from Nethesis we have no plan to develop a POP3 connector application with Getmail, like used in NS7. It seems to be no longer developed since 2021. Fetchmail, another similar tool we adopted in the past for NS6, seems still alive.

However we decided to drop them both, because of the way they work: sending again a message via SMTP after it has been finally delivered is not correct and leads to problems. Instead the Imapsync method, which copies messages only via IMAP is more predictable and safe.

Before taking this path, we checked the protocols supported by ISPs: where POP3 is still available, IMAP is present in >99% of cases too. We encourage our customers to take this path.

This does not prevent someone else to develop another connector application for NS8.

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pity for me and a few others, for sure. and how did it work also with scanning emails for virus, spam etc. the imapsync is just copie the emails, right? i test it and i see no recognition in RSpamD or the clamav system. In the NS7 mail System was it also possible to have white and blacklists, is there something i did not see in NS8?

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Exactly, once they are delivered, messages are considered good. Here we make some assumptions:

  • Mail providers nowadays enforce a good AV and Antispam before delivering messages to mailboxes.
  • RSpamd needs the original SMTP envelope to be effective: checking the message again after delivery has less chances to detect spam than the SMTP-facing server.

Yes, the feature is present since the first Mail release, but the Filter manual page didn’t say it. Now it has been rewritten for the upcoming Mail 1.4 release: it explains how it works. Here’s a preview link Mail — NS8 documentation

In some cases an email client, recipient, or sender must bypass the filter checks: the Bypass rules section allows to define a set of rules based on the follwing criteria:

  • Sender IP address or network (CIDR format).
  • Complete sender email address.
  • Sender email domain.
  • Complete recipient email address.
  • Recipient email domain.
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  • Will it be possible to receive emails in a distribution group?
  • Will any filters/rules present in the mailbox work?

Or will there be the same limitations present in NS7?

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The implementation is really different, so I’d expect different limitations.

As messages are copied from a remote mailbox to a local one, if a group of users wants to read it you could leverage IMAP ACLs and configure a shared mailbox.

Sieve filters are triggered by new message deliveries (LMTP): they do not run when messages are pushed/copied (IMAP).

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These are the same problems that were with getmail on ns7

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I had a look at fetchmail recently and following /etc/fetchmailrc worked for me to retrieve from provider via IMAP and send to NS8 via SMTP.

set postmaster "markus@domain.local"
set bouncemail
set no spambounce
set properties ""
set syslog
set daemon 300

poll             mail.domain.tld
localdomains     domain.local
protocol         IMAP
envelope         "X-Envelope-To:"
user             'markus'
pass             'secret'
to               * here keep ssl

To install fetchmail on an ns8 host:

RH based: dnf install fetchmail
Debian: apt install fetchmail

I don’t know if it really makes sense to have an app for that but there’s already a fetchmail-docker so it should be possible. The harder part (for me) is the user interface.
The advantage would be that the fetchmail configuration is included in NS8 backup.

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not sure that i wrote it right. In NS 7 i had a filter for allow from, deny from and a possibility to block, is this coming with the new Mail 1.4? i have the “new” version 1.4.0-dev.5 and i found an allow, an deny but no block a domain or an adresss… and will it be possible to migrate the RSpamD Database from NS7 to NS8?

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i will try it in a second, thank you again Mr Markuz !!!

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You’re welcome but it’s just a first working draft, for sure we need to find a good configuration.

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No this (rarely used and frequently abused) feature is not planned in the NS8 Mail application. Possible alternatives are

  1. customize Rspamd configuration: adding a dynamic map and managing it with the Rspamd UI
  2. use Crowdsec to ban an IP
  3. use a Sieve filter to drop messages from certain users/domains

As said in another thread the Bayes DB is migrated.

We are working to update the Migration manual page, this is a draft of what is not migrated after 1.4 Release: NethServer 7 migration — NS8 documentation

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Let’s try to solve the problem without installing additional packages on the host. Let’s try to do it with containers!

Alpine Linux has a fetchmail package: Alpine Linux packages

To start with an Howto also ns8-scratchpad + an “Alpine with fetchmail and cron” container could be enough for a PoC.

Further resources:

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