Duplicate mails in inbox

This morning our mailbox inboxes suddenly were filled with hundreds of mails that were already processed earlier, so some update that took place last night on subscribed nethserver must have caused this.

Does anyone else see this? Is there an easy fix? I am dealing with it with a thunderbird addon, but it is a bit difficult to explain this to our users, and some of them have a problem of finding which mails they already have replied and which ones not…

Our situation: We have an internal domain served by our neth mailserver. But those mails are not for external communication and not affected. We further have an external domain where nethserver has configured a connector for each of our users external mailadress, which pulls mails from an external server by imap.

This morning the inbox folder (and only the inbox folder) has hundreds of mails pulled again that were already processed and were thus partially moved to subfolders.

your issue is not clear enough, sorry you should formulate again

IIUC your external nethserver use a connector (which one, I assume getmail) and this connector is pulling again and again the same emails. This is what I understand.

Hi stephdl and thanks for asking. Yes, I configured a connector for each user so it is getmail that is used. Everything worked perfectly for months. Apparently the morning I wrote this post, there must have been an update which probably made neth mailserver “forget” which mails were already downloaded, as all mails in inbox were downloaded again and that produced duplicate mails in our users inboxes.

Things like these usually happens when there’s is a problem on the system to which you connect to via POP3 (i.e. the email provider).
That’s why I always advise against using the POP3 connector (except for brief periods during migration of services).

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Hi @Elleni,

Even though I dislike answers which suggest to do do it all in a different way myself, can only agree with @filippo_carletti advise from own experience. Being a former small business owner went through the evolution of e-mail:

  • from none in the mid 90’ ;
  • to one “info” mailbox ;
  • to a hosted pop3 account for every employee ;
  • to a hosted imap account for every employee ;
  • to the “get-mail” fetch pop3 solution ;
  • to a full fetched mail-server (at the time M$ smallbusiness with exchange).

The main reason to invest in a ‘real server’ at that time was the cumbersome functioning and maintenance of the fetch pop3 e-mail setup.

There are compelling reasons to use NS as a frontend-mail-server such as a blocked port 25, high availability or a dynamic public IP address to name a few.

For me as home user it is the (theoretically) dynamic IP address. Theoretically because it has never changed, however the ISP has the right to do so. The solution I’m every happy with is the little known service batched smtp also referred to as queued smtp some hosting providers have.

Grtz Mark

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I am with you Filippo, but it would have been a too big step for our boss. Thus the instruction was to keep the external mail provider, while all other ressources were newly engineered, new ad domain, nethserver nextcloud for caldav/carddav, neth ips, proxy, etc. etc, so I came up with this solution, to get a domain ourdomain.xy served by neth while keeping ourdomain.yz hosted by external email provider.

My task was to have an imap server on a nethserver enabling us to do additonal filtering on emails, but not to transfer the external domain to our nethserver.

Initially I thought maybe mailproxy could be used to intercept and filter by rspamd but as this module is not available on the new interface, I thought it maybe will be depricated soon, and decided for the actual setup.

I will discuss your advice, and will maybe be able to convince our CEO to serve our external domain directly by our mailserver. Maybe we could make something like primary mailserver for ext. domain: our nethserver, secondary mailserver: the external one. But this will take some time for the decision, and in the meantime we will use the time to gain further confidence in our neth environement I have setup. There is also another problem with our hosted nethserver. I realized that as I am hosting my private domain mailserver on the same hoster. They have poor ip reputation at M$ and thus from time to time mails to their domain are rejected and I regularely have to ask our hoster to delist their ips from blocklist of Microsoft. And this would be a nogo for our boss, that mails would partially not get delivered, thus he wants to keep the external mailhoster for the moment.

As the setup with connector (we use imap not pop3 for fetching with getmail) worked nicely for months, I was wondering if it could be possible that one of the latest updates which were installed automatically by subscribed nethserver could have caused this, but I understand and thank you for the hint that it also could be a problem not related to neth at all but on the external imap server. Thanks for the pointer.

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Hi @Elleni,

The environment someone has to work in can be challenging at times. :slight_smile:

To your suspicion a update may have bugged you, I can only say this is the beauty of open source… (EDIT) Here resent the changes to imapsync.

As an amendment to my suggestion: It may be possible to use the smpt server of your registrar / hosting provider as the (smtp) smarthost on the NS VPS as a solution for the bad IP reputation.

__ OT __
Over here in the Netherlands the mail-only subscriptions with limited mailboxes / storage-space providing (B)SMTP service can be quite affordable, I pay €6,= ex 21% vat (DE: MwSt) a year for this service, unlimited number of send/received emails.

EDIT: @Elleni does not use getmail, probably imapsync

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Smarthost was not possible to configure with the actual provider as they do not allow to send emails by one user, for another emailadress so we cannot configure a single smarthost user to send for all our emailadresses. I think it is getmail (was this updated shortly?), as I had made this post some time ago. In connector protocoll is configured for the download.

getmail has no changes since Apr 10, 2020

(AFAIK (AsFarAsIKnow) getmail is a pop3 connector…)


This leaves us with what Filippo said - possibly a problem with external imapserver. Thanks for your help in analyzing.