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?