Why does Outlook show horizontal lines between the blocks of your newsletter?
In the desktop version of Outlook, you sometimes see one or more thin lines between the blocks of your newsletter, in the colour of the background. Outlook adds these lines itself. You can only remove them by slightly adjusting your newsletter.
The desktop versions of Microsoft Outlook (2007, 2010, 2013, 2016 and 2019) display emails using the Word rendering engine instead of a web browser. This limits the possibilities, meaning all kinds of workarounds (‘hacks’) are needed to show your newsletter as you designed it in Laposta.
No hack works for these horizontal lines. On this page, Microsoft responds and acknowledges the problem, but does not offer a solution for it. As soon as a solution does become available, Laposta will implement it.
Fixing the lines by adjusting your text
In many cases, it helps to add or remove some text. Sometimes it also helps to adjust the line spacing. Make a few small changes here and there and check via a testmail in Outlook whether the lines have disappeared.