Problems sending an Alert to a single internal address

[Anonymous]

I have used the Send Alert function several times and I have never had a problem. but for some reason there is a single email address that will not receive the alert, when I look in the activity log it get this as an error: 
550 [internal] [oob] The message was blocked by the receiver.   Not sure why this is happening 

[Anonymous]

It is possible that the intended recipient has emails from the Marketo user blocked in their Outlook.  Have them whitelist the Marketo user email address and see if that solves the problem.

[Anonymous · Accepted solution]

It may be Outlook, or some other anti-spam device or service present in your network.  Modern anti-spam systems can include the ability for individual users to white- or black-list email addresses, domains, key words, etc.  You could try asking your IT team about what is running in your email environment and ask them if they can help configure it properly so that your colleague can receive their wanted mail!

[Anonymous]

Thanks for your help, it looks like it is an exchange setting that was only effecting a certain email alias