Max Email Attachment Size

Short answer: There is no single maximum email attachment size. The real limit depends on the provider and the exact account you send from.

Published on•
Last updated on•
15 min read
Christin Baumgarten

Operations Manager

Michael Bodekaer
Reviewer

Founder, Board Member

Abraham Ranardo Sumarsono
Tester

Full Stack Engineer

Authored By Christin Baumgarten Operations Manager

Christin Baumgarten is the Operations Manager at Mailbird, where she drives product development and leads communications for this leading email client. With over a decade at Mailbird — from a marketing intern to Operations Manager — she offers deep expertise in email technology and productivity. Christin’s experience shaping product strategy and user engagement underscores her authority in the communication technology space.

Reviewed By Michael Bodekaer Founder, Board Member

Michael Bodekaer is a recognized authority in email management and productivity solutions, with over a decade of experience in simplifying communication workflows for individuals and businesses. As the co-founder of Mailbird and a TED speaker, Michael has been at the forefront of developing tools that revolutionize how users manage multiple email accounts. His insights have been featured in leading publications like TechRadar, and he is passionate about helping professionals adopt innovative solutions like unified inboxes, app integrations, and productivity-enhancing features to optimize their daily routines.

Tested By Abraham Ranardo Sumarsono Full Stack Engineer

Abraham Ranardo Sumarsono is a Full Stack Engineer at Mailbird, where he focuses on building reliable, user-friendly, and scalable solutions that enhance the email experience for thousands of users worldwide. With expertise in C# and .NET, he contributes across both front-end and back-end development, ensuring performance, security, and usability.

Max Email Attachment Size
Max Email Attachment Size

Short answer: There is no single maximum email attachment size. The real limit depends on the provider and the exact account you send from. 1 2 5

For example, personal Gmail and Yahoo Mail allow 25 MB, Outlook.com webmail allows 25 MB total email size, and iCloud Mail allows 20 MB. 2 4 6 7

This guide shows the current limits for Gmail, Outlook, Yahoo, iCloud, Proton, Zoho, and Microsoft 365, then walks you through simple ways to send large files in Mailbird without bounce-backs.

What’s new

In February 2026, Google said it was rolling out 50 MB direct Gmail attachments for Enterprise Plus accounts, while personal Gmail still caps attachments at 25 MB. That means the maximum email attachment size depends on the account behind the address, not just the app on your screen. 1 2

TL;DR

  • There is no single maximum email attachment size; the real limit depends on the provider and the exact account you send from. 1 2 5
  • Personal Gmail and Yahoo Mail allow 25 MB, Outlook.com allows 25 MB total email size, and iCloud Mail allows 20 MB. 2 4 6 7
  • Some Google Workspace Enterprise Plus accounts now have an option for 50 MB direct Gmail attachments, but that does not apply to every Gmail account. 1 2
  • Microsoft 365 / Exchange Online defaults to 35 MB sent, and admins can set limits from 1–150 MB. 5
  • MIME base64 encoding makes encoded data about 33% larger, so a file that looks under the limit can still fail once it is wrapped for email. 11
  • If the file still does not fit, switch to a share link such as Google Drive, OneDrive, or Mail Drop instead of retrying the same attachment. 2 4 8
  • Another client, company policy, or recipient system may be stricter than the published limit on your side. 5 8

Before you start

What you need

the file you want to send, the exact email account you will send from, and either built-in ZIP tools or a cloud-link option.

Time

one short session for documents and photos; longer if you need to re-export a large video.

Difficulty

Easy.

Cost

Usually free. You may need paid cloud storage only if you are out of space.

Safety

Do not send passwords in the same email as the file. If the file is sensitive, share access codes in a separate channel. Providers can also block risky attachment types even when the file is small. Gmail, for example, blocks executables and some password-protected archives. 12

Maximum email attachment size by provider

Use this table to check the published limit for the account you actually plan to send from.

Account or service Limit to remember What happens if you go over
Gmail (personal) 25 MB total Gmail uploads the file to Google Drive and inserts a link. 2
Gmail (Google Workspace Enterprise Plus accounts) Up to 50 MB direct attachments Google announced a February 2026 rollout for Enterprise Plus accounts. Ask your admin whether it applies to your domain. 1
Outlook.com 25 MB total email size This includes text plus inserted and attached files. OneDrive links do not count toward the email size limit. 4
Microsoft 365 / Exchange Online Default 35 MB sent; admins can set 1–150 MB Exchange Online defaults to 35 MB sent and 36 MB received, but admins can raise or lower the limit and some clients may still be stricter. 5
Yahoo Mail 25 MB total Yahoo counts the sum of all attached files in one message. 6
iCloud Mail 20 MB message size If you send from Apple Mail or iCloud.com, Mail Drop can handle attachments up to 5 GB. 7 8
Proton Mail 25 MB outgoing Incoming mail can be up to 50 MB. 9
Zoho Mail (personal) 20 MB total email size Paid plans can send larger files as links from the composer. 10

Gmail (personal)

Limit to remember
25 MB total
What happens if you go over
Gmail uploads the file to Google Drive and inserts a link. 2

Gmail (Google Workspace Enterprise Plus accounts)

Limit to remember
Up to 50 MB direct attachments
What happens if you go over
Google announced a February 2026 rollout for Enterprise Plus accounts. Ask your admin whether it applies to your domain. 1

Outlook.com

Limit to remember
25 MB total email size
What happens if you go over
This includes text plus inserted and attached files. OneDrive links do not count toward the email size limit. 4

Microsoft 365 / Exchange Online

Limit to remember
Default 35 MB sent; admins can set 1–150 MB
What happens if you go over
Exchange Online defaults to 35 MB sent and 36 MB received, but admins can raise or lower the limit and some clients may still be stricter. 5

Yahoo Mail

Limit to remember
25 MB total
What happens if you go over
Yahoo counts the sum of all attached files in one message. 6

iCloud Mail

Limit to remember
20 MB message size
What happens if you go over
If you send from Apple Mail or iCloud.com, Mail Drop can handle attachments up to 5 GB. 7 8

Proton Mail

Limit to remember
25 MB outgoing
What happens if you go over
Incoming mail can be up to 50 MB. 9

Zoho Mail (personal)

Limit to remember
20 MB total email size
What happens if you go over
Paid plans can send larger files as links from the composer. 10

Important: Some providers publish a message limit, not a raw file limit. Outlook.com counts text, inserted items, and attachments together; Exchange Online says its limits include attachments; and iCloud Mail caps incoming and outgoing message size at 20 MB. Microsoft and Apple also note that another client or recipient system may be stricter than the number you see here. 4 5 7 8

To verify: if the account belongs to work or school, confirm the current limit with your admin or IT team before the final send. Google Workspace and Microsoft 365 can both use plan-specific or admin-set limits. 1 5

How to send large files from Mailbird without guessing

How to send large files from Mailbird without guessing

  1. Identify the exact account you will send from

    In Mailbird, open a new message and check the From address before you attach anything. If you have more than one inbox connected, note the provider behind that address—Gmail, Outlook.com, Microsoft 365, Yahoo, iCloud, Proton, or something else.

  2. Match that account to a real limit

    Use the table above instead of guessing. If you send from Gmail, check whether it is a personal account or a managed Google Workspace account. If you send from a work Microsoft account, treat the limit as company-controlled until you confirm otherwise. 1 2 5

  3. Measure the file before you attach it

    On Windows, right-click the file and choose Properties . On Mac, Control-click the file and choose Get Info . If you plan to send multiple files, add their sizes together before you continue.

  4. If the file is close to the limit, stop there

    Email systems do not send raw files exactly as they sit on your drive. MIME base64 encoding makes encoded data about 33% larger, so a file that looks “under the limit” can still fail once it is wrapped for email. 11

  5. Compress the file or folder into a ZIP

    For documents, spreadsheets, and folders, create a ZIP first. On Windows, right-click the file or folder and choose Send to > Compressed (zipped) folder . On Mac, Control-click and choose Compress . Then check the new ZIP size before you attach it.

  6. Make the file smaller if ZIP does not help

    For photos, export a smaller copy. For PDFs, use a reduced-size export. For video, trim the clip or export a lower-resolution copy. Re-check the new file size after each export so you do not keep guessing.

  7. Split big batches into separate sends

    If one email contains too many files, send two clearly labeled messages such as Part 1 of 2 and Part 2 of 2 . This works better than retrying the same oversized message again and again.

  8. Switch to a link when the attachment is still too large

    If the file still does not fit, upload it to a cloud drive and send a share link instead. Gmail can upload oversized files to Google Drive and insert a link, Outlook.com lets OneDrive links bypass the email size limit, and Apple’s Mail Drop can send attachments up to 5 GB when you use Apple Mail or iCloud.com. 2 4 8

  9. Set permissions before you send

    Open the share settings and confirm that the recipient can actually view or download the file. If the file is private, choose the narrowest permission that still lets the recipient do the job, such as view only or specific people .

  10. Add the file in Mailbird and send a test first

    In Mailbird, attach with the paperclip or drag the file into the compose window, then send a test email to yourself or a teammate. Open it from a different browser or device and confirm that the attachment downloads or the link opens before you send the final message. 3

  11. Send the final message with a fallback sentence

    In the email body, name the file and say what to do if the attachment fails, for example: “If the attachment does not come through, use the link below.” That one sentence saves a second round of back-and-forth when a recipient’s system is stricter than yours.

Why the max email attachment size can change

The method works because a size limit can be enforced at more than one layer: the provider, the email client or webmail, the company admin, and the receiving system. Checking the provider first, leaving room for encoding overhead, and switching to a link before you hit the ceiling prevents most bounce-backs and stalled uploads. 5 8 11

What can change your max email attachment size

Attachment rules can change by plan, rollout status, client, admin policy, and recipient system. Google’s newer 50 MB Gmail attachments apply to specific Enterprise Plus accounts, Microsoft business limits can be customized by admins, and cloud-link behavior depends on the service you use. If a send fails below the number in the table, re-check the provider’s current help page or ask your IT admin. 1 5 8

Troubleshooting large email attachments

Symptom Likely cause Fix
You see “attachment too large” before the message sends Your provider or app limit is lower than you expected Check the exact sender account again, then compress, split, or switch to a share link.
A 24 MB file still fails in Gmail The total message crosses the limit after email encoding or because you attached more than one file Remove the attachment, zip it, or send a Drive link instead. 2 11
The message sends from webmail but fails in a desktop app The desktop app or company policy is stricter than the mailbox service Try the provider’s webmail once. If it works there, ask your admin or keep using a link for large files. 5
The recipient says the attachment never arrived The receiving server or app has a smaller limit than yours Resend with a share link or split the files into smaller messages. 5 8
Your ZIP file is barely smaller The file is already compressed, like JPG, MP4, or many PDFs Export a smaller version instead of zipping again.
The recipient gets “Access denied” on the link The sharing permission is wrong Open the file’s share settings, add the recipient, and send the corrected link.
The file is small but the provider still blocks it The attachment type is considered risky, or the archive is password-protected Use a secure file-sharing portal or cloud link instead of trying to force the attachment through. Gmail, for example, blocks executables and some password-protected archives. 12
The message sits in Drafts or Outbox The upload did not finish or the connection stalled Remove the attachment, restart the send, and use a link if the network is slow.

You see “attachment too large” before the message sends

Likely cause
Your provider or app limit is lower than you expected
Fix
Check the exact sender account again, then compress, split, or switch to a share link.

A 24 MB file still fails in Gmail

Likely cause
The total message crosses the limit after email encoding or because you attached more than one file
Fix
Remove the attachment, zip it, or send a Drive link instead. 2 11

The message sends from webmail but fails in a desktop app

Likely cause
The desktop app or company policy is stricter than the mailbox service
Fix
Try the provider’s webmail once. If it works there, ask your admin or keep using a link for large files. 5

The recipient says the attachment never arrived

Likely cause
The receiving server or app has a smaller limit than yours
Fix
Resend with a share link or split the files into smaller messages. 5 8

Your ZIP file is barely smaller

Likely cause
The file is already compressed, like JPG, MP4, or many PDFs
Fix
Export a smaller version instead of zipping again.

The recipient gets “Access denied” on the link

Likely cause
The sharing permission is wrong
Fix
Open the file’s share settings, add the recipient, and send the corrected link.

The file is small but the provider still blocks it

Likely cause
The attachment type is considered risky, or the archive is password-protected
Fix
Use a secure file-sharing portal or cloud link instead of trying to force the attachment through. Gmail, for example, blocks executables and some password-protected archives. 12

The message sits in Drafts or Outbox

Likely cause
The upload did not finish or the connection stalled
Fix
Remove the attachment, restart the send, and use a link if the network is slow.

Best options for different file types

Fastest fix

Skip compression and send a cloud link first when the file is obviously large, such as video or a big photo batch.

Best for office documents

Put related Word, Excel, and PDF files into one ZIP, then give the ZIP a clear name like Proposal-2026-07-15.zip .

Best for photos

Export smaller copies for email and keep the full-resolution originals in your main storage.

Best for private files

Use a restricted share link or your company’s secure portal, then send any passcode in a separate channel.

Make-ahead, storage, and scaling tips

  • Make-ahead: Keep an “email-ready” folder with smaller PDFs, reduced photos, and pre-zipped document sets so you are not resizing files at the last minute.
  • Storage: Keep the original file and the send-ready version as separate copies. Delete broad share links after the recipient confirms the download.
  • Scaling: If several people need the same large file, upload it once and send one view-only link instead of attaching the same file to every message.

Frequently asked questions about maximum email attachment size

What is the maximum email attachment size?

There is no single limit. Common published limits include 25 MB in Gmail and Yahoo Mail, 25 MB total email size in Outlook.com, and 20 MB in iCloud Mail. Some work or school accounts can use different limits.

Sources: 1 2 4 5 6 7

What is the maximum email attachment size in Gmail?

Personal Gmail allows 25 MB. Some Google Workspace Enterprise Plus accounts now have a newer option for 50 MB direct attachments, but that does not apply to every Gmail account.

Sources: 1 2

Is the maximum email attachment size the same as the message size limit?

Not always. Some providers publish a total message size limit that includes attachments and other content. Outlook.com uses a 25 MB total email size limit, Exchange Online says its limits include attachments, and iCloud Mail caps message size at 20 MB.

Sources: 4 5 7

Why does a file under the limit still fail to send?

Email adds encoding overhead, and the app, admin policy, or receiving system may be stricter than the limit you expected.

Sources: 5 11

Do multiple attachments count toward one limit?

Usually yes. Gmail and Yahoo Mail count the total size of the attachments in one message, and Outlook.com applies a total email size limit.

Sources: 2 4 6

How do I add a large attachment in Mailbird?

Open a new message in Mailbird, then add the file with the paperclip or by dragging it into the compose window. If the file is too large to send as a normal attachment, use a share link instead.

Sources: 2 3 4 8

How do I send a file larger than the attachment limit?

Use a cloud link instead of a normal attachment. Gmail can upload oversized files to Google Drive, Outlook.com can use OneDrive links, and Apple Mail or iCloud.com can use Mail Drop for attachments up to 5 GB.

Sources: 2 4 8

What if the recipient uses a smaller provider limit?

Your message can still bounce or lose the attachment even if your side accepted it. Send a smaller file or use a share link.

Sources: 5 8

Quick checklist

  • I checked which account I am sending from.
  • I matched that account to a real limit.
  • I measured the total size of every file in the message.
  • If the file was close to the limit, I compressed, reduced, or split it.
  • If it was still too large, I switched to a share link.
  • I checked sharing permissions before sending.
  • I sent a test and opened it from another device or account.
  • I included a fallback line or link in the final email.

Mailbird brings this into one desktop inbox for Windows and Mac, so you can set it up in minutes.

Sources

  1. Google Workspace Updates — Sending larger attachments in Gmail: New 50MB limits for Enterprise Plus customers
  2. Gmail Help — Send attachments with your Gmail message
  3. Mailbird Support — How to Add Attachments in Mailbird Next
  4. Microsoft Support — Unable to attach files in Outlook.com
  5. Microsoft Learn — Exchange Online limits
  6. Yahoo Help — Message size limits in Yahoo Mail
  7. Apple Support — Mailbox size and message sending limits in iCloud
  8. Apple Support — Mail Drop limits
  9. Proton Support — Attachment and email size limits
  10. Zoho Mail Help — Email attachments, attachment limits and options
  11. RFC Editor — RFC 2045: Internet Message Bodies
  12. Gmail Help — File types blocked in Gmail