What format and size can images be?
In Laposta, you can use images in gif, jpg and png format up to a maximum of 12 MB. Other file types, such as a pdf or a Word document, can be shared via a link in your newsletter.
Does an image span the full width of your newsletter? Then aim for 600 to 620 pixels, which is the standard width for newsletters.
Preferably do not place images larger than 1 MB: the larger the file, the longer it takes before your subscriber sees the image in your newsletter. Is your image much wider or larger than necessary? You can resize it first in the image editor.