It's not only in my WA but also in hers. And you don't need WA or internet since the files you send are also automatically stored locally. Esp. in buildings with a lot of concrete, the connection can be lost and then you stand there; "sorry need to go outside". And the backup is not only iCloud (from the iPhone) but also Google Drive (from her Android phone). In e-mail systems there can always be issues with attachments, esp. in the Yahoo App they get corrupted rather easily, and if the e-mails are years old, it takes forever to reload them. I never use WiFi I don't know btw; the 4G is dirt cheap and fast enough.