Interesting text. So it is supposed to be required -we still don't know how
Imail handles it- but however it is controversial.
To add more information on this topic I found two different ways to
configure MX records from what I believed are serious and recognized
companies, organizations or services.
###First one:####
To have one or more MX records, but every MX record has multiple IP records
Examples: hotmail.com, microsoft.com, yahoo.com
Here the Ips of just one of their various MX records
Microsoft.com
querying to 10 mailb.microsoft.com solves
IP=131.107.3.123
IP=207.46.121.51
Yahoo.com
querying to 1 mx1.mail.yahoo.com solves
IP=67.28.113.10
IP=67.28.113.11
IP=4.79.181.14
IP=4.79.181.15
Hotmail.com
querying to 5 mx1.hotmail.com solves
IP=64.4.50.99
IP=65.54.166.99
IP=64.4.50.50
IP=65.54.252.99
###Second:#####
Instead of having various IPs per MX record, they have various MX record,
one IP per MX record
IBM.COM
instead of having various IPs in every MX record. It has 11 MX records with
priority 10
10 e4.ny.us.ibm.com. IP=32.97.182.144
10 e5.ny.us.ibm.com. IP=32.97.182.145
10 e6.ny.us.ibm.com. IP=32.97.182.146
10 e31.co.us.ibm.com. IP=32.97.110.129
10 e32.co.us.ibm.com. IP=32.97.110.130
10 e33.co.us.ibm.com. IP=32.97.110.131
10 e34.co.us.ibm.com. IP=32.97.110.132
10 e35.co.us.ibm.com. IP=32.97.110.133
10 e1.ny.us.ibm.com. IP=32.97.182.141
10 e2.ny.us.ibm.com. IP=32.97.182.142
10 e3.ny.us.ibm.com. IP=32.97.182.143
Google.com
It doesn't have various IPs in their MX recors. It has 4 MX records instead
10 smtp1.google.com. IP=216.239.57.25
10 smtp2.google.com. IP=64.233.167.25
40 smtp3.google.com. IP=216.239.57.26
40 smtp4.google.com. IP=66.102.9.25
Gmail.com
05 gmail-smtp-in.l.google.com. IP=64.233.185.27
10 gsmtp171.google.com. IP=64.233.171.27
10 gsmtp171-2.google.com. IP=64.233.171.114
10 gsmtp185.google.com. IP=64.233.185.27
10 gsmtp185-2.google.com. IP=64.233.185.114
My question is how Imail handles every case. From what I recall correctly in
Version 7.1 there was a bug corrected when DNS queries are executed so MX
records would be used in priority order
But I am not sure how Imail handles things when an IP in the Mx record
fails. Does is look for the next IP listed if any, before going to the next
Mx record in the priority order (assuming there is more than one Mx record)
Btw: I am running version 8.15.
-Luis Arango
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:IMail_Forum-
> [EMAIL PROTECTED] On Behalf Of Rod Dorman
> Sent: S�bado, 21 de Mayo de 2005 03:37 p.m.
> To: [email protected]
> Subject: Re: [IMail Forum] How Imail handles delivery when the MX record
> has multiple IPs
>
> On Saturday, May 21, 2005, 15:03:59, Panda Consulting S.A. Luis Alberto
> Arango wrote:
> > ...
> > Is that a standard Imail Behavior? To connect it uses the first IP
> reported
> > on every MX record, and if the connection fails it goes to the next MX
> > record, but doesn't even try to use other IPs in the same MX record
> found
> > first?
>
> RFC 2821 Simple Mail Transfer Protocol
> section 5. Address Resolution and Mail Handling
>
> Although the capability to try multiple alternative addresses is
> required, specific installations may want to limit or disable the use
> of alternative addresses. The question of whether a sender should
> attempt retries using the different addresses of a multihomed host
> has been controversial. The main argument for using the multiple
> addresses is that it maximizes the probability of timely delivery,
> and indeed sometimes the probability of any delivery; the counter-
> argument is that it may result in unnecessary resource use. ...
>
>
> --
> [EMAIL PROTECTED] "The avalanche has already started, it is too
> Rod Dorman late for the pebbles to vote." � Ambassador Kosh
>
>
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