SMB solo SysAdmin here. I have a decent amount of experience with Exchange, but need to be sure we have no issues as we get into our busy season of the year (we're a greenhouse). Our sales staff keeps coming to me with stuff like this:

"So-and-so sent this email on Tuesday and we just got it today (Friday)! What's wrong with our email server?!" (email was an @mail.com address, BTW. "Free" ad-driven service, probably garbage and not suited for business)


"This is the second week in a row this person's email didn't come through! Please fix this!!" (email address was @suddenlink.net)

So, more to the point, my questions are:

  • If the Microsoft Online Connectivity Analyzer (https://testconnectivity.microsoft.com/) says we have no issues with inbound/outbound SMTP, then the problem is either their email server or just human error, right?

  • Similarly, our transaction time (according to http://mxtoolbox.com/diagnostic.aspx) is about 7.5 seconds, which is maybe not the best, but surely wouldn't cause a 24-48 HOUR delay, right?

Lastly, We also use an Untangle UTM for anti-spam (paid version), BUT I have whitelisted the addresses in question and also didn't find them in the spam quarantine.

Thanks for your help, I appreciate it!


Things to check:

Is it being blocked by your spam filter? Do the senders have a lot of links and images in there emails? Do these domains send out a lot adds in general? (this can land them on a black list and you may need to manually allow them in your spam filter)

I deal with this a lot where I work and it is almost always because the vendor was blacklisted or they had a lot of unnecessary junk in the email. Usually you allow them once in your spam filter and be done with it. Also it they could be gray listed and put on a delayed delivery. But if the emails aren't in your spam or exchange then it is most likely on the sender's end you can also try to get them to send a plain text email (with no html or images or links)


The Microsoft Online Connectivity Analyzer can tell you if there are general deliverability/connectivity issues but it can't tell you the disposition of a particular email sent from a specific sender to a specific recipient. Here are a couple of things you can do:

Enable Protocol Logging on your Receive connector and check the SMTP Receive logs.

Use the Message Tracking Tool.

Use the Tracking Log Explorer.

The simplest method would be to search the logs for email from the specific sender.


The first thing I would be looking at is the headers of one of these "delayed" messages. That will show you where the delay is. Users like to complain about the network when it is more often than not their fault.

Identify where the delay (if any) is coming from then you can work from there.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.