What is Fetch > Automatically in iPhone in Settings > accounts and passwords?

I'll try to break down the process more finely. Fetch causes the phone to go and ask a server if there is anything new. It does that at whatever time interval you specify (e.g., 15 minutes).

With Push, the server sends a Notification to the phone that new information (email, contacts, etc) is available. The phone then asks the server for the updated information. So Push and Fetch are similar; with Fetch the clock determines when to check for new data; with Push a Notification prompts the phone to check for new data, which it usually does immediately.

Apple explains that option at the very bottom of the screen.

Fetch is not the same as Push. With the former, your iPhone is requesting that the data be sent to it. With the latter, your iPhone will receive data when Apple decides to send it to you.

Tesserax wrote:

Apple explains that option at the very bottom of the screen.

Fetch is not the same as Push. With the former, your iPhone is requesting that the data be sent to it. With the latter, your iPhone will receive data when Apple decides to send it to you.

Just for clarification, shouldn't that read "your iPhone will received data when the email provider decides to send it to you"? I was under the impression that Push was controlled by the email provider who is not always Apple. Or have I misunderstood?

At present, I haven't seen anything from Apple that fully describes these options, so I won't be able to answer your question "officially."

However, there are numerous article on the Internet if you do a search. One example is:

New Data in iOS 11: Push or Fetch in iPhone, iPad - howtoisolve.com

Tesserax wrote:

At present, I haven't seen anything from Apple that fully describes these options, so I won't be able to answer your question "officially."

However, there are numerous article on the Internet if you do a search. One example is:

New Data in iOS 11: Push or Fetch in iPhone, iPad - howtoisolve.com

Thanks! That's an interesting read.

(And I know I can get a bit detail fussy!)

If I understand this feature correctly, Fetch Automatically is not the same as push. Normally you set a time interval (I have mine set to 30 min), so mail will request updates (or Fetch them) from the email servers I use every 30 minutes. If you choose “Automatically”, your mail app will still Fetch updates from your email providers servers, but it will only do this when your device is plugged in and on Wi-Fi (both conditions must be met). I usually only plug my phone in at bedtime, so if I chose this option, my mail app would only Fetch updates once a day (at bedtime, when my phone is both on Wi-Fi and plugged in. This option would save a lot of data transfer and battery power compared to fetching on a timer, but would also mean I wouldn’t receive important emails throughout the day, but instead would only get them once a day at bedtime. Honestly, I don’t know anyone who would be able to use this feature on a regular basis, but I can perhaps see the advantage if traveling overseas where data charges can be quite expensive. This option would prevent cellular data Fetch, and would only Fetch over Wi-Fi (no data charges on Wi-Fi). Other than this type of travel situation, I can’t think of any other time I would use this.

Thank you for the correction!

Yes, you have stated the way Push works much more accurately than I had. Thanks for making that clearer as the OP did indicate other email providers in their post.