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Problem now that we've updated our PTR records

Posted on 2011-09-20
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Last Modified: 2012-05-12
We, for as far back as I'm aware (5 years) never had our reverse lookups for our mail server setup.  It was simply going out the default IP address of our external block of IPs and the PTR record was mapped to the default Comcast value.  We since changed our outbound mail flow to another IP and updated the PTR record of Comcast to match the HELO/EHLO value (for some clients in China would were using reverse lookups as the poor man's SPAM filter which it is) we've had problems with other customers (mostly in the USA) that are now rejecting our emails because it looks like our PTR records no longer match what they used to be.  

This is why I didn't want to touch this in the first place.  Where fixing something causes other people's systems to 'break' to which you can do nothing about....?

Well, that's why I'm posting this.  Is there anyway to hasten or mitigate the problems that these occasional external customers are now having?  Any global way I can make these changes?

I'm assuming no, but please inform me of whatever you guys are aware of; including how long you think it'll take before these problems go away?  When people setup their mail servers to cache PTR records is there a time limit on that cache?  

I certainly hope so, or else I'm going to have to be contacting a lot of various IT departments from all these companies.
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Question by:ChocolateRain
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by:mmaris
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Papertrip earned 500 total points
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What needs to match are the A record and the PTR record for your sending server.  I wouldn't worry too much about receivers who block on HELO mismatch -- if they are doing that then they are blocking TONS of legitimate mails.  A big "problem" with email delivery is that unless you have a contact on the other end, you can't fix their bad practices.

When people setup their mail servers to cache PTR records is there a time limit on that cache?  
Yes, the TTL value of the PTR record dictates a maximum time the record can be cached.
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