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question re reverse MX records

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ImInAfrica View Drop Down
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    Posted: 08 January 2008 at 8:57am
Could anyone shed some light on reverse mx records and RFC.
We have a supplier that has a very funny setup for sending emails.
their Mail From: command is from an email address which doesn't have a MX record.
However when they send the email the headers in the email indicate the correct email addresses. the domain used on the "Mail From:" is different to the one used in the "From:" in the email header.

They claim that no RFC specifies that a sender email address must have a mx record.
They are quiet a big supplier to our business (kind of the only supplier for this particular service), and refuse to change the behavior of their setup.

Any ideas, comments, suggestions?

Thanks
Amir

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dcook View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dcook Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2008 at 9:40am
We have had simular issues and just whitelist the offender if we know the backround like this client.  We have a hard enough time changing ourselves much less our clients.  I have a handfull of clients that have custom spam filtering for simular issues also. I can't say on the RFC, but you might search the web for the answer.
 
 
Dwight
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Desperado View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Desperado Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2008 at 11:09am
Originally posted by ImInAfrica ImInAfrica wrote:

They claim that no RFC specifies that a sender email address must have a mx record.
Amir,
 
They are correct on several levels that an MX record is not required by RFC. 
 
Originally posted by ImInAfrica ImInAfrica wrote:

Any ideas, comments, suggestions?
 
I believe Dwight answered this best ... work around it with a white-list entry because technically, by even testing for a "proper" MX, (And please remember that I pushed for this feature and I use it) we are not following any RFC but any truly responsible administrator that truly want's his mail delivered will correct this fine point.  BUT .... In the words of Alvin Lee ... "I can not change the world ... so I leave it up to you"!
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LogSat View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2008 at 11:54am
Amir,

The supplier is correct. The RFC 2821 does not *require* an MX record. However many mail servers will be rejecting their emails, as that RFC was written before spam was ever a problem, and things have changed since.

Having a valid reverse DNS entry for the mail server is not required by that RFCs either, but many providers are rejecting emails if it's not present.

If the provider has sloppy administrators, they can remain without MX records, but will most likely not be able to send emails to many customers.
Roberto Franceschetti

LogSat Software

Spam Filter ISP
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