Who This Is For / When to Use
Users sending emails with attachments from Kyrios.
Teams experiencing email bounces due to attachment size limits.
Anyone needing to send files larger than standard email limits.
How Email Attachment Size Limits Work in Kyrios
Email providers enforce maximum message size limits for security and performance reasons.
If an email exceeds the recipient provider’s limit, the email will fail to deliver and return a bounce error.
Kyrios does not bypass provider limits.
Kyrios Email Attachment Limit
Maximum direct email attachment size: 20 MB
What happens above 20 MB:
The file is automatically uploaded to the Media Library and inserted into the email as a download link instead of a file attachment.
Supported Email Provider Size Limits (Reference)
Common provider limits include:
Gmail: 25 MB per email (sent or received)
Outlook / Hotmail: 10 MB per file attachment
Yahoo Mail: 25 MB per email
AOL: 25 MB per email
Zoho Mail: 12 MB per email
Mailgun: 25 MB per message
If the recipient’s provider limit is lower than Kyrios’, the email may still bounce.
What Happens When a File Exceeds the Limit
When you attempt to attach a file larger than 20 MB:
The upload continues normally.
Kyrios displays a notice that the file will be sent as a Media Library link.
The recipient receives a secure download link instead of an attachment.
Uploading Files When Composing Emails
When adding files to an email, you can choose:
Upload from System – Upload a new file from your device.
Choose from Media Library – Insert an existing file already stored in Kyrios.
Files added to SMS messages or oversized email attachments are always delivered as links.
Common Email Bounce Error Messages
If an email exceeds a provider’s size limit, you may see errors such as:
“Attachment size exceeds the allowable limit”
“552: Message size exceeds maximum permitted”
“System Undeliverable, message size exceeds outgoing message size limit”
“The size of the message you are trying to send exceeds the global size limit of the server”
Bounce notifications appear in the Conversations tab.
Why Kyrios Uses Media Library Links
Prevents email delivery failures.
Avoids manual file compression.
Eliminates reliance on third-party file sharing.
Ensures secure, trackable file hosting inside your account.
Improves email performance and reliability.
Video Upload Enhancements (Emails Only)
When videos are uploaded to the Media Library and used in emails:
Kyrios automatically generates a GIF-style thumbnail.
Clicking the thumbnail opens the hosted video.
Improves visual engagement without increasing email size.
FAQ
What is the maximum file size I can attach to an email?
The maximum direct attachment size in Kyrios is 20 MB. Larger files are sent as Media Library links.
What happens if my email exceeds the file size limit?
The email will bounce and return an error message in your Conversations tab.
Can I bypass email attachment size limits?
No. Email provider size limits cannot be bypassed.
How can I send files larger than 20 MB?
Kyrios automatically uploads large files to the Media Library and inserts a secure download link into the email.
Does Mailgun support large email attachments?
Mailgun supports a maximum message size of 25 MB.
Are Media Library links secure?
Yes. Files are hosted inside your Kyrios account and delivered via secure links.
Can I track if a recipient accessed a file?
Kyrios does not track file downloads. Some external storage providers may offer analytics, but Media Library links do not include download tracking.
Do large attachments work in SMS?
All files sent via SMS are delivered as links through the Media Library.