HOWTO - Create receive connector for Office 365
When using our Spam Filtering Service with Office 365. We recommend making two adjustments in Office 365:
- Creating a Connector
- Configuring Connection Filtering
Create a Connector
- Log in to your Exchange Admin Center in Office 365.
- Select mail flow and then connectors.
- Click the "+" to start the process:  
- Define the mail flow scenario for this connector.  Set From: to Partner Organizaion and set To: to Office 365: 
- Name the connector and enter a description:   
- Identify the partner organization by IP address:  
- Click the "+" to start entering IP addresses:  
- Use the list of CIDR networks found here: What IP addresses does ETRN deliver e-mail from? to enter the correct IP addresss:  
- Requre TLS:  
- Review and save the connector:  
- Review your connectors:  
Configuring Connection Filtering
- Log in to your Exchange Admin Center in Office 365.
- Select protection and then connection filter.
- Click the edit icon: 
- Select connection filtering:  
- Use the list of CIDR networks found here: What IP addresses does ETRN deliver e-mail from? to enter the correct IP addresss:  
- Review your connection filtering: 
We welcome any feedback. Thank you for being a ETRN customer. Please contact us if you have any questions.
We Answer Your Questions: FAQ
Q: What is the maximum e-mail attachment size?
A: The ETRN.com e-mail servers do not limit the size of individual e-mail attachments. The ETRN.com e-mail servers do impose a 400 MB maximum total message size limit. Individual customers can choose a smaller message size limit. We can also customize the handling of "oversized" e-mails. Please contact us to discuss your specific needs. A couple of important facts:
1. Attachments are typically encoded in what is called Base64[1]. As a result, the actual length of MIME-compliant Base64-encoded binary data is usually about 137% of the original file size.
2. E-mails often contain both plain text and HTML components. This also increases the overall size of the e-mail.




