Really weird exchange issue, 1 domain out of the whole internets having issues send to us...

MasterPlan1

MasterPlan1

MasterPlan1

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So, background, our CEO's wife's companies e-mail used to be hosted with us, but she moved away to a hosted exchange infrastructure a while ago, and now she's having issues sending emails to people within our company (CEO's PA, CEO himself...)

I can't seem to work out why, our setup is 2xTrend IMSS boxes which sit as our SMTP gateways and Exchange 2003, I can't see anything which is still in reference to her email within Exch SysMan, nor within Trend, so I'm confused as to where the issue lies with us, we've tested emailing from her domain to any other domain (gmail, hotmail etc) and she can send with attachments fine. But when she sends to us, the mails are either really delayed, or having the attachments stripped.

Upon investigation with people from the hosted exchange company, they say that they're getting timeouts when sending to us, what would cause this on just one domain...? Also, the one thing that I've seen which could possibly have an effect, but I doubt it, is the MX records on the CEO's wife's domain is set up as our tertiary and quaternary MX records, which is our ISP's backup SMTP in case both of our IMSS boxes are down, that's it.

As mentioned, I can't find anything in Exch relating to this domain anymore, but if there would be some residual left overs of it about, where would they be? I've checked in recipient policies, SMTP routing groups, everywhere I can think of but can't find anything.

Any help would be much appreciated as I'm getting some stick from my boss as he's getting a LOT of stick from her as she's quite a demanding woman. :)

Thanks
 
Have you run some message tracking on emails that have been sent to your exchange from hers? Are all of the emails being sent from the hosted one to your exchange from addresses that were previously on your exchange? If so is there any way you can test it with a new address?
 
I've tracked from us to them, and they're receiving fine, it's them to us, I've requested all the logs they can find regarding mail going from her to us...

The one thing which I can think of is their servers are having issues connecting to our 1st/2nd MX record, and are going to our 3rd/4th which are seemingly dead according to testexchangeconnectivity.com as they are our old ISP's SMTP servers.

Basically, I'm just confused as **** regarding this issue, I don't know where to look or what to do. I'm going to request an account on one of the other domains that they host on their hosted solution to see if it definitely is their servers connecting in to us, or what.
 
If the latter of the MX records point to dead servers then surely have them deleted from the domains records?

This might help solve the problem. Dodgy MX is often the cause of mail delivery issues although given the fact that the domain has been migrated away from your systems to their new ones it could be other things.

Is the domain still set as authoratitive for your exchange servers? (Does it think it's still meant to be handling the domains email?) I used to work for a hosted exchange provider and although I'm no Exchange Guru, this used to be a cause for issues when people were delivering mail to our servers after migrating elsewhere.

Euology might be able to help more as his exchange knowledge is better than mine and he still works at my ex-employer.
 
Have you examined the email header to examine the routing of any of the delayed inbound which have been received?
Can you whitelist her in Trend if it's stripping attachments?
 
So the issue turned out to be skewed settings on the different sites, one trend server was set to be 1024 connections and 15m SMTP timeout, the other 5 connections, 30s timeout, I put them both to the corp settings again of 100 connections and 15m timeout, after that stuff started filtering through.
 
Yup shame i only just read this thread, almost without fail if mail is being adulterated in some way, E.G. attachments removed it'll be intermediary devices/software causing the issue.
Though sometimes with domain moves it can be things like reverse DNS as a lot of anti spam appliances use it to verify the sender.
 
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