On Fri 23 Feb 2018 at 12:53:34 (+0000), Brian wrote: > On Thu 22 Feb 2018 at 11:58:18 -0600, David Wright wrote: > > > On Mon 19 Feb 2018 at 18:39:02 (+0000), Brian wrote: > > > On Mon 19 Feb 2018 at 10:23:56 -0600, David Wright wrote: > > > > > > > $ cat /etc/mailname > > > > alum > > > > > > Debian's exim4 README says that mailname should be a FQDN. I find that > > > useful for sending mail to "anotheruser". > > > > Sorry, but I haven't been able to work out what you mean. > > Is "anotheruser" a username on the same system, somebody or > > some machine on the LAN, or something different? > > Exim will qualify all unqualified addresses with mailname. "anotheruser" > could be a user on the system or have an email account elsewhere. > With mailname as gmail.com a mail sent to or cc'ed to tom123 would go to > tom...@gmail.com.
In the long distant past, I had bar.ac.uk in /etc/mailname, and foo.bar.ac.uk as the canonical name in /etc/hosts. Before the firewalls went up, foo.bar.ac.uk (and a group of other hosts) would all resolve, and that's probably a common situation for exim4 users. Naturally, most of my emails would be to addresses like a.n.ot...@bar.ac.uk and s...@bar.ac.uk, so I could write just a.n.other and spqr in the composer and it would get qualified for me. Now I'm a home user, that situation doesn't pertain. The only common denominator in email addresses now is @. I have a set of mail alias files that translate from, say, isp to Unlimited Web Hosting UK Ltd <ad...@unlimitedwebhosting.co.uk> and so on for all the people I have emailed regularly since 1998. So, having dreamed up alum.dreamtup, how often would I expect to benefit from baz being turned into baz.dreamtup? > > This is a genuine query. If I'm missing out on some useful aspect > > of writing in a domain, I'd like to know what it is so I can try > > using it. (I have a spare domain registration handy as it happens.) > > The mailname needn't be the canonical_hostname, although exim will > indeed set it up with this when it is installed and mailname does not > exist. Easily changed. Yes, but to what (that's of any use or benefit)? > > > But mailname has nothing to > > > do with domain as enquired about by Jeremy Nicoll. > > > > The contents of /etc/mailname is the answer to this question: > > "It should be the single, fully qualified domainname (FQDN)." > > so, because the domain is empty, the FQDN will be the same as > > the hostname. I was merely showing that to be the case here. > > Yes. I don't think this disadvantages the majority of users. It is only > when setting up an MTA that some thought has to be put into what purpose > you want mailname to serve. A single word entry, the hostname, say, > would not suit me. I refer again to the question I tried to answer: "What, on a home LAN, is that used for?" Obviously I don't know your relationship with cityscape.co.uk but it's a company domain. There's really only one person on lionunicorn.co.uk and that's me. (My wife uses her institutional address.) About the only local emails here are from root. > > As pointed out elsewhere, mailname can be used to generate > > Message-IDs (mutt does) which might not be globally unique, > > A Message-ID is not used to transport a mail, so how it is generated is > not of great importance. As it happens, I generate my own through mutt. And they reveal a domain that looks as though there are few users whose unqualified names need that particular domain to be added to them. (I'm obviously guessing here.) > > not something to concern most home users, and it can be > > mitigated. It's also used as the envelope-from, it appears, > > between the mail client and exim which can rewrite it. > > That's exim qualifying an unqualified address. It doesn't qualify it, it rewrites it. It finds the "FQDN" that's in /etc/mailname, strips it off and replaces it with dc_readhost. > > I guess that if you submit mail directly from, say, mutt to > > a remote smarthost, it would be a good idea to place an > > email address into /etc/mailname. I wasn't aware that mutt read /etc/mailname, and it's not in the man page, but it can use the value of envelope_from_address instead of the sender if use_envelope_from is set. However, it's some years since I tried sending emails with its smtp_url. I prefer to stick them in exim4's queue and have a log entry kept. > I think it is always a good idea to have a FQDN in /etc/mailname, > irrespective of what is in /etc/hosts. I don't think I've seen a good explanation of why though. However, at least one problem might now be solved, with the recent decision on .home, .corp and .mail. Cheers, David.