If you’re sending emails to a recipient that uses Office 365 / Hotmail / Outlook / Exchange and they are not receiving your email, this is actually a fairly common report. First, we encourage you to open a support ticket and give us a message similar to this:

“We sent an email from _____ to _____ on {recent date), with subject _____. We did not receive any error back, and they claim to have not received it. Can you check for me?”

We want to prepare you for the most likely answer. When these variables align, we notice a 100% success rate in our response being the same: We delivered it successfully, their mail server accepted it, and whether or not the end user has it in their mailbox (inbox or spam folder) is not within our knowledge or influence. They will need to reach out to their IT department.

This is because Microsoft is the only well known email provider that is also well known to accept email and then not deliver it. They’ve been doing this for years. They will not acknowledge it, they will not admit to doing it. Yet, you can plainly see that they do. Take a look for yourself:

Mail not received, outlook.com response to sending server with Queued – Microsoft Community
Email accepted by hotmail but not delivered – Microsoft Community
Messages reported as 250 queued for delivery, but never received when – Microsoft Community
Sendgrid says emails Delivered but customers with – Microsoft Community
Email accepted by hotmail but not delivered – Microsoft Community

We could go on all day, but the pattern is clear. It doesn’t matter that these emails come from MXroute, or from anywhere in particular. This happens without any clear reason, without any error being given, and without any insight from the recipient provider who will not even acknowledge that it happens. So while we want you to let us prove to you that we did our job, we want to prepare you for the extreme probability that we’ll tell you we did and that we have no ability to influence it beyond that point.