This article explains how to copy a link in the iOS Mail app on your iPhone or iPad. Instructions apply to any iPhone running iOS 9 through iOS 12.
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Copying a URL from the Mail app on an iPhone or iPad can be done with a single tap. There’s also a hidden menu that can be opened by long-pressing the link.
Open the Mail app and tap the email with the link you want to copy to open it. This can be from any email provider that you access through the Mail app on your phone, including iCloud, Gmail, and others.
Lightly press the URL link in the email until a new menu appears with several options, including Copy.