How Can I Permanently Save an iPhone Message?by John Lister ; Updated September 19, 2017
With the iPhone being such a multimedia messaging tool, many messages are fine to delete once they are received and dealt with, but you may want to keep other messages permanently for future reference or simply nostalgic purposes. How to do so depends on the type of message. These tips are for messages received through the iPhone's default applications. They may work as described or in adapted form for applications you download from the iTunes store.
SMS Text Messages
All text messages on your iPhone are automatically copied to your computer whenever you back up your phone by connecting it to your computer and using iTunes (rather than backing up online via iCloud). In Windows 7 and 8, you will usually find the backups at C:\Users > [your username] > AppData > Roaming > Apple Computer > MobileSync > Backup. The backup files will be in an encrypted format, so you must use an independent PC application, such as iExplorer, to open the messages in a readable form. Read reviews carefully before choosing such an application, as performance varies.
iMessage is an Apple feature that sends messages directly from one iPhone to another over the cellular data network rather than as an SMS. As a result, you do not have to pay text charges to send or receive the message. The iPhone treats the sent or received iMessage in the same way as SMS text messages, and they are included in the backup. You can therefore read and permanently store iMessages in the same way as you can with ordinary text messages.
If your cellular service provider does not allow you to store voicemails permanently, you still have several options for doing so. One is to extract the saved message from your iTunes backup (in the same way as you can with text messages) using an application, such as iExplorer; note that this only works for messages still on your phone at the time you made the backup. A second option is to use an audio cable from your iPhone's headphone socket to the audio input on your computer, play back the message on your phone and record it with an audio recording application, such as Windows's built-in Sound Recorder, on your computer. (Note that you cannot simply record on the iPhone itself using the Voice Memo app, as the app shuts off when you make a phone call, including a call to your voicemail service.) A third, more drastic, option is to use a service, such as Google Voice, that lets you use a single number for multiple devices, including your iPhone, and allows you to access voicemails on a computer and save them as audio files.
iPhones can only collect emails from existing accounts. If you use a webmail account, your message will usually be accessible permanently from any device you use to access the service, unless and until you actively delete it, or you reach the (usually large) maximum limit for messages on the account. If you are not using a webmail account, the easiest option is to open the message in Mail on your iPhone, tap the flag icon at the bottom of the screen, then tap "Mark Unread." You can then download and open it on a computer using your dedicated e-mail software, which should allow you to keep it permanently. Note that whatever email account type you have, you can prevent your iPhone from automatically deleting messages. To do so, tap "Settings," then "Mail, Contacts, Calendars" and make sure "Ask Before Deleting" is switched to the On position. Once you have done this, the iPhone will store all read messages unless and until your iPhone's storage is completely full.