On 08/17/2010 08:47 AM, Gordon Messmer wrote: > On 08/16/2010 10:46 AM, JD wrote: >> Clearly, a full setup of DNS server for your domain >> must be set up, per this wiki, along with mx records ...etc. >> >> Does this prevent one from settiing up and using sendmail >> on a LAN to send and receive email to/from the outside world? > Not by itself, but I don't like the advice in that tutorial. It > suggests a configuration with a catch-all address. Long-term, you'll > find that you have to turn this off or else your catch-all will receive > an enormous amount of spam sent by spammers who used a dictionary attack > and found that every address they test is valid on your system. Without > a catch-all, there's no purpose in using the virtual user feature at > all, so the howto is somewhat more complicated than it needs to be. > > Beyond that, it does not address several practical concerns with setting > up a mail server. First, you'll need a static address and a proper PTR > for it. You won't be able to set up a PTR without a static address, and > if the reverse lookup for your IP address isn't valid, many systems will > refuse your mail. The reverse lookup (PTR) for your address must be a > hostname that resolves to your IP. > > aa.bb.cc.dd -> PTR myhost.example.com > myhost.example.com -> A aa.bb.cc.dd > > You should also look up your IP address on a blacklist watcher: > http://www.dnswatch.info/dns/rbl-lookup > > If you're listed in one of the dynamic IP blacklists, you want to set up > a smart host through which you'll relay mail. Many sites will otherwise > reject your messages. Likewise, if your ISP prevents you from making > outbound connections to port 25, you'll need to use a smart host, > because you couldn't send mail any other way. > >> I understand that some things need to be set up so that sendmail >> sends headers that use a routable IP address as the source of >> the message. Is it possible to make sendmail use my router's >> public IP address in the message headers? How? > No, that's not quite right. Sendmail should be configured to use a > valid hostname for HELO, but the IP address will be recorded in a header > which is set by the receiver of the message. You can't do anything to > change that. Well, that's very interesting. I am on the verge of giving up. Re: a.b.c.d ==> valid.host.name and valid.host.name ==> a.b.c.d does not seem to apply to the google smtp server I use for Thunderbird. To wit: $ nslookup > smtp.gmail.com Server: 156.154.70.1 Address: 156.154.70.1#53 Non-authoritative answer: smtp.gmail.com canonical name = gmail-smtp-msa.l.google.com. Name: gmail-smtp-msa.l.google.com Address: 74.125.127.109 > 74.125.127.109 Server: 156.154.70.1 Address: 156.154.70.1#53 Non-authoritative answer: 109.127.125.74.in-addr.arpa name = pz-in-f109.1e100.net. Authoritative answers can be found from: > pz-in-f109.1e100.net Server: 156.154.70.1 Address: 156.154.70.1#53 Non-authoritative answer: Name: pz-in-f109.1e100.net Address: 74.125.127.109 So, Thunderbird client does not seem to mind that reverse lookup does not match the name smtp.gmail.com -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
