Sometimes an email loses its importance shortly after it is sent, such as an email asking you to go to lunch once the afternoon begins. But other times, it is helpful or even necessary to preserve an email — perhaps even as evidence, such as an email to or from opposing counsel that is an exhibit to a discovery motion. Here is a tip for converting an email message to a PDF file on the iPhone or iPad, so that you can then preserve that PDF version of the email. The technique is similar on both the iPhone and the iPad. And unlike the tip that I shared a year ago (which only worked on an iPhone that supports 3D Touch), this tip works on either an iPhone or iPad running iOS 10 (released September 13, 2016) or later.
On the iPhone, start by looking at the email that you want to preserve in the Mail app. At the bottom of the screen, the fourth icon is an arrow that you tap to Reply to a message. Tap that button, and the third option is Print. Tap the Print button.
Tapping print brings up the Printer Options screen. Ignore the options at the top of the screen and focus instead on the print preview at the bottom of the screen. Use two fingers to do a reverse-pinch on that image; start with your two fingers together and then pull them apart on the screen. This tells your iPhone to enlarge that print preview to full screen.
Note that if you are using a newer iPhone that supports 3D Touch (iPhone 6s or newer), instead of doing the reverse-pinch gesture, you can just press down on the small print preview image to open it in the full screen print preview mode. Whether you use 3D Touch or reverse=pinch is up to you; the result is the same.
This print preview screen shows you a PDF version of your email. Now, you just need to do something with it. If you look at the bottom left corner, you will see a share button (the box with the arrow coming out of it). Tap that button to do something with the PDF file such as open it in another app (such as an app that handles PDFs), email the PDF file, save it to Dropbox, etc.
When you are finished doing whatever you want to do with that PDF version of the email, cancel out of all of the screens by tapping the arrow at the top left, then the cancel button at the top left.
Here is how to do the same thing on an iPad. Start by tapping the reply arrow at the top right of the screen. Then tap Print, the third option in the pop-up menu.
This brings you to the Print Options screen. Again, ignore the stuff at the top and reverse-pinch the preview on the bottom part.
Now you will see a full-screen version of the preview of the document. Tap the share button at the top right to see a pop-up menu of options, and choose what you want to do with the PDF version of the email — email that PDF file, open it in another app, etc.
Again, when you are done, just cancel out of the screens to return to the point where you are looking at the email in the Mail app.
Although particularly useful when working with emails, you can use this trick in other parts of iOS too, as long as you have the option to print something. For example, if you have an image in Photos on your iPhone or iPad that you want to quickly convert to a PDF file, just select the option to print the photo, reverse-pinch on the preview, and then act upon the resulting PDF file containing the image. Want to convert a note in Apple's Notes app to a PDF? Just tap the share button while you are looking at a note, tap the Printer icon, and then follow the directions above.
What if you are using an app that doesn't have a print function but you really want a PDF version of whatever you are seeing on the screen? You can take a screen-shot of the current screen by pressing the power and the home button at the same time. This puts an image in your Photos. Then follow the instructions above to convert to PDF — choose the option to print the photo, etc.
Note that sometimes, in some apps, the resulting PDF file isn't perfect. For example, if you are looking at a web page in Safari, you can tap the share button and then select print and then create a PDF file, but the resulting PDF file will often look very different than the website, sometimes completely stripping off the top of a web page. You are better off using a dedicated PDF app that is made to do a nice job converting a web page to a PDF file. PDF PROvider is one such app that can do this, but I know that many others can too. [UPDATE: A reader just informed me that DAR Software, the maker of PDR PROvider, is shutting down operations and will soon pull this app from the App Store. So while PDF PROvider is still working for me, I can no longer recommend it. I know that many other apps can also prepare a PDF of a web page; if you know of one that is worth recommending, please let me know.]
But when it comes to emails, this simple trick typically does a nice job of converting an email to PDF format, perfect when you want to preserve that email or use it as an exhibit.