We're using the email template "Get Started" and I uploaded a header image with the size 1071x370 px.
I sent a sample to my Outlook account and the header looks the way it should:
But when I send a sample to the Outlook account of my colleague, it looks this way:
So there is a part missing on the right and left border.
Does anybody have an idea why this is happening and how I could solve this problem?
There's a couple of other examples of similar issues in community; you might be able to find the solution to this in those threads.
If you can't, we'll need you to share the code for this to be able to provide more assistance. It's likely that the issue is going to be some MSO specific code. It would be helpful if you could tell us which version of outlook your colleague is using, and whether they have any magnification settings in place.