This is an issue that I have been plagued by for years and I am really trying to find the cause.
I have had this issue on my old site running Joomla 3 but have migrated to WordPress and still find this to be an issue when mailing users via this plugin.
If I manually send emails to users, there is no issue displaying any images within the body of the message.
If I send mailout to users via acymailing v9 the emails work and display the images fine on most email clients but always on macOS mail and iOS mail the images are "missing" and instead show a question mark.
I am sure I will be told this is an apple issue or something, but I have 6 mail accounts and have never seen an issue where the images don't show other than my mailouts so there must be something going on. For reference I am not embedding the images, they load from the server. I can send as attachments but this slows down the sending and also causes any replies from the mailouts to include a dozen image attachments.
