Hello @RobertG63 ,
This is a function of the receiving email programs, which always try to include previews of text from emails after the subject lines and preheaders. The only way I can really recommend if you want to avoid this, would be to have your subject line and preheader combo long enough to take up that space. However, even this wouldn't necessarily work the same for each email program / app, as it's dependent on the recipient's settings and text sizing. There is no setting on our end to prevent this kind of default functionality of receiving email programs.
Some people and organizations will add an extremely long set of spaces on the end of their preheaders to prevent any text from the email showing, or they will send image-only emails. Neither of these are best practices, and are more likely to trigger spam filters.
This is not true. The same thing is happening to me, but I notice other emails I receive in the same email program don't have this issue. Even with really short preheader text. I've been messing with this for over an hour .. tried putting an image at the top of the email to block it, but it still finds the first line of my email and appends it to the end of the preheader text. Adding spaces does not work either, even if you put a character at the end of the spaces. The spaces simply get cut out.
Like the OP mentioned, very undesirable!!
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