I'm having an issue where outgoing emails sent through our CRM system are displaying the incorrect address for one of our customers.
The Return-Path value in the outgoing email header contains an address like sendername=company.com__<random letters>@<random letters>.crmdomain.com and this value is being displayed as being the 'from' address, instead of the address set as actual 'from' value.
We use DKIM keys, and this only occurs for one of our customers. Could this be due to their email client/server and is there anything we can do to handle this on our end?
This is most likely caused by their mail system configuration, and to fix this, you will probably need to work with their IT staff.
Do you know what mail system they use? Both their transport agent (mailserver) and their user agent (mail program on PC) could be at fault.
If your customer is tech-savvy, he/she might be able to extract mail headers from one of the mails you sent them, and forward this information to you for better analysis. However, depending on the type of client and your relationship to them, this may violate their corporate security rules, so you should check with the people in charge at their company.