A mail client that does not ask for alternate email

You're looking for a mail client that doesn't ask for an alternate email address when sending an email. Here are a few options:

1. Thunderbird: Thunderbird is a popular open-source email client that allows you to customize the sending process. You can disable the "Alternate Email" field by going to Tools > Account Settings > Composition > Advanced and unchecking the box next to "Use alternate email address".
2. Microsoft Outlook: Outlook allows you to customize the sending process by going to File > Options > Mail > Send and unchecking the box next to "Use my alternate email address".
3. Gmail: If you're using Gmail as your email provider, you can disable the "Alternate Email" field by going to Settings > General > Signature and unchecking the box next to "Alternate email address".
4. ProtonMail: ProtonMail is a secure email provider that allows you to customize the sending process. You can disable the "Alternate Email" field by going to Settings > Account > Advanced and unchecking the box next to "Alternate email address".
5. Tutanota: Tutanota is another secure email provider that allows you to customize the sending process. You can disable the "Alternate Email" field by going to Settings > Account > Advanced and unchecking the box next to "Alternate email address".

Keep in mind that disabling the "Alternate Email" field may affect the functionality of certain email features, such as email forwarding or auto-responders.