不使用SMTP发送应用程序的邮件可以使用其他协议或工具来实现。以下是几种常见的解决方法：

1. 使用SendGrid API发送邮件：

import sendgrid
from sendgrid.helpers.mail import Mail

def send_email(api_key, from_email, to_email, subject, content):
    sg = sendgrid.SendGridAPIClient(api_key=api_key)
    message = Mail(
        from_email=from_email,
        to_emails=to_email,
        subject=subject,
        plain_text_content=content)
    response = sg.send(message)
    if response.status_code == 202:
        print("Email sent successfully.")
    else:
        print("Failed to send email.")

# 调用示例
send_email("your_api_key", "from@example.com", "to@example.com", "Hello", "This is the content of the email.")

2. 使用Python内置的smtplib库以外的库发送邮件，如yagmail库：

import yagmail

def send_email(sender_email, sender_password, receiver_email, subject, content):
    yag = yagmail.SMTP(sender_email, sender_password)
    yag.send(to=receiver_email, subject=subject, contents=content)

# 调用示例
send_email("sender@example.com", "sender_password", "receiver@example.com", "Hello", "This is the content of the email.")

3. 使用第三方邮件客户端程序如Outlook或Thunderbird的API或插件发送邮件。具体操作可以参考相应的文档和示例代码。