Hoe to include an image in writer for mailmerge purposes

I drafted an announcement in LO-Write and included an image at the end (a logo) in png format. When I sent the announcement using mail merge wizard to a series of mail addresses, the image does not appear in the mail. For testing reasons I sent the mail also to my other mail box where the logo is just visible, it’s also visible on that mail box on my iPhone.
I spent an evening to try another format (jpg), inserting within the wizard guidance etc, nothing really helped even checked with another addressee to make sure.
My question is how to put the image in the document so it will appear on each sent mail?

I’m using Libreoffice on Open SUSE Tumbleweed on an old HP Compact 5800 Core2 duo 3GHz with 2 GB RAM.
The outgoing server configured in LO does not belong to the same account as my the inboxes (Gmail account), does this make a difference?