On Vi, 22 oct 21, 11:09:14, Martin McCormick wrote: > One more question I should know the answer to but am not sure of. > The debian Buster system I use for email presently uses fetchmail > to get mail from the ISP and is configured to use that ISP's > smarthost for out-going mail. I do not want to effect > (= muck this up) this functionality because it works well for > now.
Then don't touch it ;) > Shouldn't I be able to install an imap server on the > debian box and forward messages of interest to it, then reach > imap4 on the private net from any system that speaks imap or has > an imap client? Of course. It's probably easiest to have the IMAP server on the same system as the local SMTP server so there shouldn't be any "forwarding" involved. Just configure both to use the same storage location. In case of different programs accessing the same mail store the maildir format is recommended (over mbox), so that would be something like /home/<user>/Maildir. > That would do what I need to do. > > When I was researching, the article in wikipedia I read > said that many commercial systems have email clients which > understand imap, pop3, etc. The systems likely to do this on our > network are a windows10 box, an iMac and maybe an iPad. The idea > would be to forward an email message needing this attention to > imap on the linux box, contact the Linux box from one of the > devices I mentioned, and download the message at which point it > would e as if that system had been hooked up to the ISP and > received it. If you mean "download" as in use something like fetchmail than I would recommend against it. IMAP was designed to keep messages on the server, the client only has its local cache. With the IMAP server on the same LAN operations should be almost as fast as dealing with locally stored mails. For comparison, I'm reading this (and many other Debian lists) via IMAP to GMX with neomutt as IMAP client. Just the debian-user folder currently has more than 38000 messages. There are occasional pauses (a few seconds or so), particularly when changing folders, but I suspect this is due to the slow local storage (the entire OS runs from a USB stick). > I was all ready to use .local as our domain name and then > I looked that up and there is a good wikipedia article which > explains how that is problematic and recommends using something > like .lan, .office or something else that isn't likely to be > registered as a top-level resolvable domain name. > > The machine I receive email on presently would be a good > candidate for running a mdns but our netgear router advertises > whatever dns's the isp uses for obvious reasons and that's fine > but it would be nice if the mdns's address could also be known to clients > on our network which could make DNS queries to each other's names > that would resolve properly. If you are referring to mDNS here, that is actually meant to work without a server[1]. It's probably also much less flexible because it's meant to work with minimal or no configuration. A good candidate for a local DNS server would be your router, provided its firmware (more accurately operating system) supports this functionality. > Is there a way to advertise the mdns so that the router > picks it up but doesn't drop the internet DNS's that we all need > to resolve the rest of the world? What is the router supposed to do with your mDNS after it "picks it up"? > I do remember when I was working, we explored open-source > network authentication systems which involved fake DNS's that one > had to advertise as such so their information wouldn't corrupt > the proper working DNS's which could really mess things up if > somebody happened to pickup and cache the wild card * that sent > all new supplicants to the authentication server after they were > already up and running. > > In our case, the corruption would be okay and done for > good reasons but the dhcp server in our router already advertises two > domain name servers so ours would have to be learned about by > discovery. It shouldn't be necessary to pass the ISP's DNS servers to all local systems because most home routers can act as a caching DNS server (I would be really surprised if yours didn't), so they can advertise themselves as DNS server for your LAN via DHCP and forward queries to the ISP DNS servers (or other DNS servers of your choice) as needed. If this is somehow not possible (why?) you could either try to change the router's firmware (e.g. to something like OpenWrt) or use another system running 24/7 for DNS and DHCP (e.g. with something dnsmasq). It could very well be the same system running the SMTP (and IMAP) server. You would probably get better, specific suggestions if you would describe your network in more detail, in particular the router (model, firmware, configuration), and other systems that are providing (or planned to do so) services for your LAN. For client-only systems the operating system and general (intended) use, e.g. "want to read local mail from here" would be sufficient. [1] https://en.wikipedia.org/wiki/Multicast_DNS Kind regards, Andrei -- http://wiki.debian.org/FAQsFromDebianUser
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