"Domain of sender address does not exist" (it does
I have had my linode up for a while now (
Each week though I get a few of these in my logs:
But (from a completely different machine):
daniel@roomatthetop:~$ dig -t MX engoi.com
; <<>> DiG 9.4.1-P1 <<>> -t MX engoi.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50953
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;engoi.com. IN MX
;; ANSWER SECTION:
engoi.com. 84087 IN MX 10 mail.engoi.com.
;; Query time: 9 msec
;; SERVER: 195.238.2.21#53(195.238.2.21)
;; WHEN: Sun Dec 16 22:56:42 2007
;; MSG SIZE rcvd: 48
Does anyone here have any clue as to what the problem might be, and how I might go about fixing it?
By the way, I don't actually know even how I have an MX record. All I have done to set up DNS for this site has been to point the DNS servers where I bought the domain to ns1.linode.com and ns2.linode.com … after that, everything just seemed to work. (Yes, I agree that that might not quite be enough …
Daniel
10 Replies
I have tried emailing the destination support address, but who knows if or when I'll get a response.
However, mail.engoi.com does not resolve to anything. Perhaps you should fix that :)
At the moment, in my DNS manager I have one MX record :
mail.engoi.com
and A/AAAA records for
engoi.com
and so on
I thought the MX was enough - does mail.engoi.com need it's own A record? Can you explain what's going on?
Many thanks!
Don't forget that the default TTL for Linode's DNS Manager is one day, so sites which have your DNS cached may take up to a day to pick up your changes.
–James
Edit:
If you need some help, hit me up on IRC.
MX = mail
A = IP
duh (ice cream => forehead)
@danmcb:
thanks guys. I needed to read up on DNS a bit … but I think I have it covered now.
MX = mail
A = IP
duh (ice cream => forehead)
8)
Not quite. An "MX" record means "send mail for this address to machine blah". You also need to tell people what the address is for "blah" and that's why you need an A record.
@irgeek:
Yes, the address you specify for the MX needs to resolve to an IP address. Also, some sites check that forward and reverse DNS match on an MX record. Assuming the forward and reverse of your IP match, you can just point the MX at that name and you should be fine.
Then those sites are broken. MX records can only point to A records (not CNAMEs) and so will frequently not match the relevant PTR record.
For incoming messages checking the IP address matches forwards and backwards is fine (so if I send from 1.2.3.4 and the PTR for that is blahblah.example.invalid then the A records for blahblah.example.invalid must include 1.2.3.4), but for outgoing messages? No, that's wrong.
@RFC974:
There is one other special case. If the response contains an answer
which is a CNAME RR, it indicates that REMOTE is actually an alias
for some other domain name. The query should be repeated with the
canonical domain name.
Let's say that I was trying to recieve email on
The remote mailserver was lookup up sub.example.com, and as I had CNAMED it to example.com, the remote mailserver was eventually checking hte MX record on example.com and then trying to deliver the email to
Now, I have this setup, which seems to work:
A
example.com ip
sub.example.com ip
CNAME
imap example.com
smtp example.com
MX
10 example.com smtp.example.com
10 sub.example.com smtp.example.com
Have I done anything wrong here that could result in misdirected mail?
It may seem to work as is, but there will be people who mysteriously won't be able to send you mail, and it won't be their fault.