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Steps to set up your corporate email account in the iOS and iPadOS Mail app. If you also want to synchronize calendars and contacts, you can use the Exchange (ActiveSync) option.
All the values you will use during setup are below. Replace yourdomain.com with your own domain name; the username is always your full email address, not just the "name" part.
The step-by-step email setup wizard asks for your email app and address, then guides you through every screen with settings tailored to your address. We never ask for your password.
Menu names change slightly with the iOS version; the order and field names are the same.

Open the Settings app and follow Apps > Mail (in older versions Mail, Contacts, Calendars), then Mail Accounts and Add Account.

Ready-made providers such as iCloud, Google and Yahoo are listed. Because your corporate address is not one of them, select the Other row at the bottom.

Tap the Add Mail Account row under the MAIL heading.

Type your name, email address and password. The Description field appears as the account name on the phone. Continue with Next at the top right.

Make sure the IMAP tab at the top is selected. Enter the same server name for the incoming and outgoing mail servers. Although the username and password appear optional for the outgoing mail server, they must not be left empty, otherwise you cannot send mail.

After saving, go back into the same account, scroll to the bottom and tap the Advanced row. The port and encryption settings are here.

Turn on the Use SSL switch and set the server port to the value below.

Go back one menu, tap the SMTP row, then the primary server, and correct it the same way.

If you typed the server name wrongly, or no certificate is defined for your domain, a "Cannot Verify Server Identity" warning appears. First check that you typed the server name as mail.yourdomain.com.
The server details are the same in all of them; only the look of the screens changes.
Outlook 365 and the new Outlook app
Classic Outlook versions (2013-2021)
Android phones and tablets
The Mail app on Mac
Windows, Mac and Linux