[Cialug] Email server

Fri May 12 19:04:11 UTC 2017

Yes, you should also verify (with the tools mentioned above) that you're
not in a "dynamic" or "dial-up" network block.

-dc

On Fri, May 12, 2017 at 1:58 PM, Matthew Nuzum <newz at bearfruit.org> wrote:

> Then you should be well situated. The nice thing about having a business
> account is that you get an SLA and Mediacom will watch the blocklists for
> you. Also, malicious spammers aren't going to sign up for it, so only
> accidental spammers will be problematic, and Mediacom will handle that too.
>
> On Fri, May 12, 2017 at 1:55 PM <khamil8686 at gmail.com> wrote:
>
> > Good point, thanks! I found I could upgrade to a business account for the
> > same price that I could rent a VPS (+$20) so figured I’d give it a shot
> to
> > try my own. I will try and see if I run into the same stuff. Time will
> > tell, I plan to set It all up this weekend 😊 We will see if I make it a
> > week or not, lol. The spammers sound pretty hardcore!
> >
> >
> >
> > *From: *Matthew Nuzum <newz at bearfruit.org>
> > *Sent: *Friday, May 12, 2017 1:52 PM
> >
> >
> > *To: *Central Iowa Linux Users Group <cialug at cialug.org>
> > *Subject: *Re: [Cialug] Email server
> >
> >
> >
> > I realize I'm coming late to the game (half the messages to CIALUG go to
> a
> >
> > "special place"). I just wanted to explicitly point out something that
> has
> >
> > been kind of said in this thread.
> >
> >
> >
> > One of the biggest challenges of running your own e-mail server is the
> >
> > blocklists. These are services that most major e-mail providers use to
> >
> > auto-block mail from untrustworthy sources. E-mail sent from IP addresses
> >
> > in the blocklist never even get to the SPAM filters, they just get
> >
> > auto-dropped or auto-rejected.
> >
> >
> >
> > Sometimes (often?) entire IP address blocks and subnets are added to
> these
> >
> > lists, and it is quite common for low-cost hosting providers to be in
> these
> >
> > blocks. One customer will send a bunch of SPAM and for a day or week or
> >
> > month an entire subnet will get blocked. If you are in the same subnet,
> >
> > this means anyone using Hotmail, Yahoo, Gmail and etc will be unable to
> >
> > send you messages or receive yours, and they/you may not even get a
> bounce
> >
> > message indicating that the delivery failed.
> >
> >
> >
> > For me, this was the last straw and I stopped running my own server. I
> >
> > don't even run an outgoing server any more. Technically, I do, but it's
> >
> > smart hosted to Send Grid or, rarely, gmail. This means if my website
> sends
> >
> > an email (contact form, error log, etc) it gets queued into Postfix which
> >
> > then forwards it to Sendgrid for delivery.
> >
> >
> >
> > Like others here, I also use GSuite in addition to Send Grid and
> Mailchimp
> >
> > for my various e-mail needs.
> >
> >
> >
> > One last footnote: If you want to run a mail-server in house, you can.
> One
> >
> > of the oldest methods of mail delivery was to have a "sometimes-online"
> >
> > host periodically connect to a remote mail-queue to fetch and send
> e-mail.
> >
> > Keeping the above in mind, it is not an issue to have a cheap VPS be your
> >
> > queue and then have your internal host connect to it to fetch e-mail and
> >
> > use the VPS as a smart-host. You could even VPN into your VPS (grin) so
> >
> > that you have an "almost-always-online" type connection. You still need
> to
> >
> > worry about reverse DNS on your VPS, but it does give you the comfort of
> >
> > having very limited processes running on that host, making it a smaller
> >
> > attack target.
> >
> >
> >
> > On Mon, May 1, 2017 at 3:26 PM David Champion <dchamp1337 at gmail.com>
> > wrote:
> >
> >
> >
> > > Technically not always your ISP, although that is usually the case. You
> > can
> >
> > > tell for sure by doing a "whois 8.8.8.8" (substitute your IP) and find
> > out
> >
> > > who owns the netblock range that you fall into.
> >
> > >
> >
> > > You can use "dig -x 8.8.8.8" to see what the current PTR is.
> >
> > >
> >
> > > mxtoolbox has a bunch of nifty tools available for doing various dns
> >
> > > queries. This Arin lookup is nice:
> >
> > >
> >
> > > https://mxtoolbox.com/arin.aspx
> >
> > >
> >
> > > -dc
> >
> > >
> >
> > >
> >
> > > On Mon, May 1, 2017 at 2:26 PM, Nicolai <nicolai-cialug at chocolatine.
> org>
> >
> > > wrote:
> >
> > >
> >
> > > > On Mon, May 01, 2017 at 12:53:59PM -0500, khamil8686 at gmail.com
> wrote:
> >
> > > >
> >
> > > > > One thing I wondered, if I set up an authoritative nameserver on
> port
> >
> > > 53
> >
> > > > > using my domain name, point dns towards there, and put reverse
> lookup
> >
> > > > > for my home mail server, would emails be rejected?
> >
> > > >
> >
> > > > > Purely an academic example that I was curious about.
> >
> > > >
> >
> > > > Well, your authoritative nameserver wouldn't be responsible for
> >
> > > > answering reverse DNS queries for your IP address; that's your ISP's
> >
> > > > job.  In other words, nobody would ask your NS for the PTR record of
> >
> > > > e.g. 53.2.0.192.in-addr.arpa.  All those queries would go to your
> ISP's
> >
> > > > nameservers.
> >
> > > >
> >
> > > > dig +short ns cialug.org.
> >
> > > > dig +short cialug.org. # currently 67.224.64.36
> >
> > > > dig +short ns 64.224.67.in-addr.arpa.
> >
> > > >
> >
> > > > Nobody asks the cialug.org nameservers questions about 67.224.64.36.
> >
> > > >
> >
> > > > To get a specific PTR record for your IP address, you'd have to ask
> >
> > > > your VPS/colo provider.
> >
> > > >
> >
> > > > Nicolai
> >
> > > > _______________________________________________
> >
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> >
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> >
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> >
> > > >
> >
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> >
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> >
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> >
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> >
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> >
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> >
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> >
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> >
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> >
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