Office 365 External Mail Flow Problem

[edsa131]

Hi, hopefully someone can help with an Office 365 external mail flow issue that started last week.

 

This problem is intermittent because some email from external domains is being received by internal mailboxes. I have checked all of the DNS records at our external DNS hosts Easily.co.uk and they seem fine, however, when I have spoken to Microsoft support they say that the MX records are not set up correctly at Easily. I then spoke to Easily and they told me that the records were fine. Nothing has changed on our internal DNS servers so I am assuming that all is fine there.

 

When an external sender sends an email to someone on our domain they are not receiving any NDRs because the email message is showing as sent in their sent messages. I am now thinking that there may be a filtering issue. We use BTNet for our internet provision so we have a CISCO 2900 Router and for our web filtering and firewall we have Smoothwall Unified Threat Management in place.

 

Has anyone experienced these issues with Office 365 Email and if so where would you recommending making checks?

 

Many thanks

 

Eddie

[Michael]

If you perform an MX lookup here by entering your domain, does the correct record show? If it doesn't, then there's still a problem at Easily.