Thanks for the suggestion. I’ve tried it by copying the iframe text from website A (where MailPoet resides) and pasting it into a text widget on Website B (where it doesn’t). That seemed to work because the widget appeared in the appropriate place with all the appropriate fields. However, when I clicked “Submit”, nothing happened and no confirmation email appeared.
I then checked my MailPoet Subscription list back on Website A and confirmed that no new user was subscribed.
I checked the src= parameter in the iframe, and the first part of the address was appropriately pointing at website A (I couldn’t interpret the rest).
I thought that there might be conflicts arising from other related plugins, such as the Mailchimp plugin on website B. I de-activated them, but still had no luck.
Suggestions?