Opera Mail's email account properties are as user-friendly to configure as setting up your email account. M2 divides your email accounts properties (or "settings") in four tabs: General, Servers, Outgoing, and Outgoing. This tutorial covers your email account's Outgoing properties.
To view or configure your email account's properties in Opera Mail, go to Tools > Mail and chat accounts.
From the Manage accounts dialog that opens, select the email account whose settings you want to configure, and click Edit.
Alternatively, double-click the email account in the Manage Accounts dialog to open Account Properties, or hit Enter while it is selected.
Click on the Outgoing tab in Opera Mail's Account Properties dialog. The settings under Outgoing do not affect the outgoing server itself (covered under Servers properties), but rather the way outgoing emails are handled before they leave Opera Mail.
The Default encoding will determine what character set Opera Mail will use when sending your emails. By default on a Windows machine (with Latin characters), Opera will use ISO-8859 - the Windows western character set. While UTF-8 is a more flexible encoding, not all email clients support it.
Unless you run into problems using ISO-8859 (or the default encoding chosen by your operating system), you should leave the settings automatically chosen by Opera.
Opera Mail offers five options on handling outgoing emails. Again, these options are handled by Opera Mail, before emails are sent to the outgoing mail server.
Opera Mail can automatically append a custom signature to your outgoing emails, and each email account can have its own signature.
To learn how to use email signatures in Opera Mail, please see the Automatic Email Signature tutorial.