I have been using Yahoo Mail for several years, and my mailbox now contains a large number of important emails, attachments, and custom folders. I want to create a local backup because I don't want to depend entirely on online account access for keeping my older correspondence. However, I am not sure which method is suitable for downloading the complete mailbox while maintaining the original email information.

I am looking for a reliable Yahoo Mail backup tool that can save emails along with their attachments, headers, and folder structure. I would also prefer having multiple output options because I may need to access some emails through Outlook or other email clients later. Manually forwarding messages or downloading them individually is not practical when thousands of emails are involved.

While researching different solutions, I came across the SysInfo Yahoo Backup Tool. It provides options to export Yahoo emails into formats such as PST, MBOX, EML, MSG, PDF, and CSV. It also supports folder selection and date-based filtering, which could help when backing up only specific mailbox data.

One thing I would like to understand is whether a Yahoo email backup software can handle large mailboxes without missing attachments or changing the folder organization. Is it possible to select Inbox, Sent, Drafts, and custom folders separately? I am also interested in knowing whether the backup process requires an app password when two-step verification is enabled.

Security is another concern because my mailbox contains personal and business correspondence. I would prefer a method that saves the data directly to my computer or external storage.

If anyone has recently backed up a large Yahoo mailbox, please share your experience. Which method worked reliably, and what precautions should I take before starting?