Are you hitting the Yahoo Mail attachment size limit when sending important files? While Yahoo enforces attachment limits for good reasons, they can be very frustrating. But that doesn’t mean you’re stuck: In this article, you’ll learn why Yahoo applies attachment size limits, what happens when you exceed them and how to send large attachments using your Yahoo account anyway!
Summary:
Yahoo restricts the maximum size of attachments you can add to an email. Currently, the Yahoo email max attachment size limit lies at 25 MB and cannot be changed.
So deal with the limit, you have two options:
➡️ Keep attachments under ~18 – 20 MB (since Base64 encoding increases file size by roughly 33%).
➡️ For larger attachments, send multiple emails or use a file-sharing platform like Google Drive, Dropbox or WeTransfer.
💡 When performing an email migration from or to Yahoo, consider these aspects to stay within Yahoo’s attachment size limit!
What Is TheYahoo Mail Attachment Size Limit?
Yahoo limits the total amount of data you can add to an email. This “attachment size limit” applies to the entire message, not just individual files. This means that you can hit the limit in two ways: By attaching one single large file, or by adding several smaller files that collectively exceed the Yahoo mail attachment size limit.
💡 The current Yahoo email max attachment size is 25 MB. This applies to both sending and receiving emails – regardless of your Yahoo account type.
Heads Up: Encoding Inflates File Size!
When adding a file to your Yahoo Mail message, your files are converted using Base64 encoding, which roughly adds 33% overhead to every file. This means that a 20 MB file is roughly 26 – 27 MB large after encoding.
➡️ This is why even files that appear smaller than the 25 MB limit can exceed the Yahoo limit!
➡️ Rule of thumb: Multiply your file size by 1.33. If it’s still smaller than 25 MB, you can safely add it. Otherwise, consider relying on one of our workarounds to send large files using your Yahoo Mail account!
Why Does Yahoo Apply Limits?
While it might be frustrating when an attachment can’t be added to your message, Yahoo has good reasons to apply a max file size limit to your email. Large email attachments significantly slow down the entire email transmission. By limitting attachments to max. 25 MB, Yahoo ensures that emails are delivered quickly and reliably, even for users on slower or unstable network connections.
Additionally, attachment size limits help Yahoo to efficiently scan every attachment for malicious content like spam or malware — the larger the file, the longer the scanning process takes. They also act as a defence against Denial of Service (DoS) attacks and help prevent “inbox bloating”. This means that the limit prevents your mailbox from getting too big too soon.
How to Change the Yahoo Email Max. Attachment Size Limit
Here’s the bad news: You can’t increase Yahoo’s maximum attachment size limit. Yahoo applies a hard limit of 25 MB for every account, and this cannot be changed.What Happens If YouExceed the Yahoo Email Size Limit?
Receiving Emails That Exceed the Yahoo Email Size Limit:
So what happens if someone sends you a large attachment that exceeds the Yahoo Mail attachment size limit? The email is rejected by Yahoo’s mail servers and will not be delivered to your inbox. Instead, the sender receives a bounce-back error message letting them know that the message exceeded the maximum allowed size.
A typical error message looks like this:
552 Message size exceeds the maximum permitted
Since the email is rejected before even appearing in your inbox, you won’t know that someone has tried to send a large message to your inbox. If the sender doesn’t alter the message (e.g. removes the attachment) and tries to send it again, you’ll never receive it.
Sending Emails That Exceed the Yahoo Email Max Attachment Size:
If you try to send an email with attachments larger than 25 MB, Yahoo Mail will prevent the message from being sent. You’ll typically see an error message directly in the compose window, informing you that the attachment exceeds the maximum allowed size.
A common error message looks like this:
The attachment exceeds the maximum allowed size
In this case, the email stays in your outbox or draft folder and is not delivered to the recipient. To send the message successfully, you’ll need to remove the oversized attachment or use one of the workarounds explained below.
Yahoo Email Size Limits &Email Migration
Yahoo attachment limits can be especially annoying when performing an email migration. The severeness of the impact depends on the direction of your email migration (from or to Yahoo). So let’s investigate both scenarios and have a look at possible workarounds:
Migrating Emails from Yahoo to Another Provider:
When migrating from Yahoo to another email provider (e.g. from Yahoo to Microsoft 365 or Yahoo to Gmail), you don’t have to worry about Yahoo’s attachment size limits. All emails contained in your Yahoo mailbox already have a maximum attachment size of 25 MB. Since most providers allow attachments of 25 MB (or even more), you can simply perform the email migration without worrying about attachment size limits.
Migrating Emails to Your Yahoo Mail Account:
Migrating your mailbox from your existing provider to Yahoo can be a little trickier, as it’s possible that your existing provider allowed attachments larger than 25 MB. This means that these emails are going to be rejected by Yahoo.
After the email migration, you’ll find one or more error messages similar to this one in MailJerry‘s migration summary:
INBOX/841 {42026170} could not append ( Subject:[=?GBK?B?yczStbrP1/c=?=], Date:["14-Mar-2026 07:16:39 +0000"], Size:[42026170], Flags:[\Seen] ) to folder INBOX: Error sending 'APPEND INBOX (\Seen) "14-Mar-2026 07:16:39 +0000" {42026170}': 40 NO Maximum size of appendable message has been exceeded
How to Resolve the “Maximum size of appendable message has been exceeded” Error:
To migrate messages with attachments larger than 25 MB to your Yahoo inbox, follow these steps:
- Download the log file from your MailJerry migration summary. It contains a list of all messages that exceeded Yahoo’s attachment size limit. If your mailbox contains many messages with large attachments, upload the log file to an AI of your choice and ask it to provide a list of all affected subjects for easier reference.
- Open the affected messages in your current email account or email client. For each message, download the attached files and then delete the attachments from the email.
- In MailJerry, click on your migration and scroll down to “Options”. Here, click on the “Sync Now” button to migrate the missing emails without attachments.
✅ MailJerry will now migrate the once rejected messages to your Yahoo Mail account.
Workarounds:How to Send Large Files Using Your Yahoo Account
The Quick-and-Dirty Fix:
Send Multiple Emails
If you need to send multiple files, each being roughly 18 – 20 MB, you can simply send multiple emails. Granted, this fix is not very elegant, but it allows you to send your files quickly, making it a great option if you’re in a rush.
ℹ️ To minimise confusion, number your emails with the current and total number of related messages so the recipient can easily verify that all data has been received.
Example: Report 1 of 3
The Professional Way:
Use a File-Sharing Service
To send messages significantly larger than 25 MB or when in a professional setting, it’s best to rely on a file-sharing service such as Dropbox, WeTransfer or Google Drive.
💡 Yahoo Mail previously offered a built-in Dropbox integration, but this feature has been discontinued. Therefore, you’ll need to use an independent file-sharing service of choice and <strong>share the download link in your email</strong>.
How to Send Large Files Using Google Drive, Dropbox or OneDrive:
- Upload the file to Google Drive, Dropbox, OneDrive, or a similar file-sharing platform.
- Share the file and set the permissions so the recipient can access it (e.g. “Anyone with the link” or invite the recipient by email).
- Copy the share link and paste it into your Yahoo Mail message.
- Send your email. Instead of an attached file, the recipient will receive a link to the download page
➡️ Now, the file can only be downloaded by people you granted access to.
⚠️ Sending Sensitive Data: Sharing Permissions
When sharing files via a file-sharing service, make sure to check your sharing settings. If you set the permissions to “Anyone with the link,” anyone who obtains the URL can download the file – which is not recommended for sensitive or private data.
For maximum privacy, use the “Share” dialog to invite specific recipients by their email address. This ensures that only the authorised person you explicitly granted access to can view or download the file.
Yahoo Mail Attachment Size Limit:Frequent Questions
Yahoo rejects my file, even though it’s smaller than 25 MB! What is happening?
This happens because of Base64 encoding. When you attach a file, Yahoo converts it into a text-based format that adds roughly 33% overhead to the file size. If you attach a 20 MB file, the actual size sent through the system is closer to 27 MB, which exceeds the 25 MB limit.
Tip: Always keep your original files at least 1/3 smaller than the limit (around 18–20 MB) to stay safe.
Does the attachment limit apply to every file I attach, or just the total email size?
The limit applies to the entire message. This includes the text in the email body and the cumulative size of all attachments. You can hit this limit by sending one larger file or by sending several smaller files that, when added together, exceed the limit.
Can I increase the attachment size limit on my Yahoo Mail account?
No. Yahoo enforces a hard limit of 25 MB that cannot be changed. If you need to send larger files, use one of the workarounds explained in this article.
If I am migrating emails to Yahoo, will my large attachments be lost?
They won’t be “lost,” but the messages are going to be rejected during the migration process. If your previous provider allowed attachments larger than 25 MB, you will likely see a “Maximum size of appendable message has been exceeded” error in your migration log.
If this is the case, you’ll need to download and delete the affected attachments and then perform a resync so that the rejected messages are migrated as well.
Is there a more professional way to send files larger than 25 MB than just sending multiple emails?
Yes. The professional standard is to use a file-sharing service. Google Drive, Dropbox and OneDrive are all common options. Simply upload your file, set the sharing permissions, and paste the download link into your Yahoo Mail message.
Does Yahoo Mail offer a built-in cloud storage integration like Gmail’s Google Drive?
No. Yahoo Mail previously offered a Dropbox integration, but this feature has been discontinued. To send large files, you’ll need to use a third-party file-sharing service and share the download link in your email.
Is it safe to share files via Google Drive or Dropbox using my Yahoo Mail account?
It depends on how you configure your sharing settings. Setting the option “Anyone with the link” makes the file accessible to anyone who happens to obtain that URL, which is not recommended for sensitive or private data.
For maximum privacy, you should always use the “Share” dialog to invite specific recipients by their email address. This ensures that only the authorised person you explicitly granted access to can view or download the file.
