If you've ever tried on your Yahoo! mailbox to attach a file larger than 25 Mb in size, you know you can't because the attachments are limited in size. Fortunately, Yahoo! Mail has integrated Dropbox and it is now possible to send larger attachments. It is also possible to save your attachments directly to your Dropbox. Make sure you've linked your Dropbox and Yahoo accounts for a smoother and easier integration.
Steps
Method 1 of 2: Attach a file from Dropbox

Step 1. Upload the file to Dropbox
You can either import the file directly to your Dropbox online account or place it in your local Dropbox folder so that it syncs with the online account.

Step 2. Log into your Yahoo

Step 3. Compose a new message
It can be any length and addressed to any number of recipients you want. If you just want to test the attachments, send it to yourself.

Step 4. Attach a file from Dropbox
In the message composition window, click on the paperclip icon to access the attachment options. Choose Share from Dropbox. A dialog box should appear to display your Dropbox folders. Browse through your folders and locate the file you would like to attach.
- You can attach multiple files at one time by selecting them. Once you select them, the files will be highlighted or checked.
- You can attach files of several formats. Music, PDFs, movies, etc.

Step 5. Click Choose

Step 6. Complete your message
The file you choose should be shared via a Dropbox link embedded inside your post. It will not necessarily be physically attached, but the file can be accessed from the given link.

Step 7. Send your message
You could send a copy to yourself in order to visualize the post and see how the link works.
Method 2 of 2: Save an attachment to Dropbox

Step 1. Log into your Yahoo

Step 2. Open a message with an attachment
All file sizes should be fine.

Step 3. Locate the attachment
It is located towards the bottom of the message. You should see a paper clip next to the file name.

Step 4. Download the attachment
Click on the link Download next to the attachment. Choose Save to Dropbox. A dialog box should appear for you to specify the location of your Dropbox folders where you want to place the file. Choose the location and click on To safeguard.

Step 5. View the attachment on Dropbox
You can upload the file from your Dropbox account online, or you can retrieve it from your local Dropbox folder after syncing is complete.