Sync my iPad & iPhone email numbers of mailings received

As described, one or other of your devices might be configured to use the older POP3 mail-protocol instead of IMAP - the latter being designed to allow access to your mail from multiple devices while keeping all devices synchronised via the Mail server.

Unless you fully understand how to manually configure your Mail account settings, simply deleting and re-adding your email account is sometimes the easiest way to resolve a problem with a Mail account. Once a Mail account is configured on your iPad, while it is possible to change account settings, iOS/iPadOS does not provide the means to convert a configured account from POP3 to IMAP or vice-versa.

After deleting the Mail account, perform a forced restart before re-adding the email account to your iPad/iPhone:

• Delete account:

Settings > Mail > Accounts > [Your Mail Account] > Delete Account

• Force restart the iPad:

Force restart iPad - Apple Support

• Add Mail Account:

Settings > Mail > Add Account

As a side note, be aware that some email providers may require the use of App Specific Passwords when accessing mail over IMAP or POP3. If this applies to your email account, you will need to generate a unique password for your iPad email account - that will differ from your normal Account Password. As examples - AOL, Yahoo, Google, Microsoft all use App Specific Passwords when using anything other than their own email client Apps.

If you need to generate an App Specific Password, you’ll need to log-in to your Mail Providers account management webpage - using a web browser - and generate the Password from the appropriate account security page.

More information about AOL’s App Specific Passwords can be found here:

https://help.aol.com/articles/allow-apps-that-use-less-secure-sign-in?guccounter=1

For Yahoo, more information can be found here:

https://help.yahoo.com/kb/SLN27791.html

For Gmail:

https://support.google.com/mail/answer/185833?hl=en-GB

Microsoft:

https://support.microsoft.com/en-us/account-billing/using-app-passwords-with-apps-that-don-t-support-two-step-verification-5896ed9b-4263-e681-128a-a6f2979a7944