Knowing the maximum email size limits for sending and receiving can help improve email reliability and reduce the risk of messages being delayed, rejected, or returned to the sender.
This guide will help you understand the maximum email size supported when sending emails from your 1-grid email service, what counts towards the size limit, and how to avoid delivery issues caused by large attachments.
What This Means
Every email service has limits on the size of messages that can be sent or received. These limits include the entire email, not just the attachment.
The total email size includes:
- The email message itself
- All file attachments
- Email formatting and encoding overhead
If an email exceeds the maximum supported size, it may fail to send or be rejected by the receiving mail server.
Understanding the Maximum Email Size Limits
Sending Emails
Emails sent through MailChannels support a maximum message size of 25 MB, including all attachments.
This means the combined size of the following cannot exceed 25 MB:
- A single large attachment
- Multiple smaller attachments
- The email content and attachment encoding
Although 25 MB is supported, sending smaller emails generally improves delivery performance.
Receiving Emails
The maximum size of emails you can receive may vary depending on the sender’s email provider, their mail server configuration, and any limits enforced by the receiving mail system.
If you are expecting a large email that does not arrive, it may have been rejected before reaching your mailbox due to size restrictions on the sending or receiving mail servers.
Steps to Managing Your Email Size Limits
Step 1: Check the Total Size of Your Email
Before sending an email with attachments:
- Check the size of each attachment.
- Remember that multiple attachments are added together.
- Allow for additional overhead created during email encoding.
Step 2: Reduce Attachment Size if Necessary
If your email approaches the size limit:
- Compress files into a ZIP archive.
- Resize large images where appropriate.
- Remove unnecessary attachments.
- Send files separately instead of in one email.
Step 3: Consider Alternative File Sharing
For very large files, consider using a secure cloud storage or file-sharing service and include a download link in your email instead of attaching the files directly.
This can improve delivery success and make downloading easier for recipients.
Important Things to Know
- The 25 MB limit applies to the total email size, not just the attachment.
- Attachment encoding increases the size of files during transmission.
- Recipient mail providers may enforce lower maximum email sizes.
- Large emails may take longer to upload and download depending on your internet connection.
- Delivery can still fail if the recipient’s mail server accepts smaller messages than yours.
Before You Move On
Before sending a large email:
- Confirm the total attachment size is below 25 MB.
- Verify you are sending from the correct email account.
- Consider whether cloud file sharing is a better option.
- Ask the recipient whether their email provider accepts large attachments if you’re unsure.
Common Mistakes to Avoid
- Assuming only the attachment size counts towards the limit.
- Sending multiple attachments that exceed the total message size.
- Forgetting that email encoding increases file size.
- Sending large multimedia files when a download link would be more suitable.
- Assuming every email provider supports the same attachment limits.
If This Didn’t Work
If your email fails to send or a recipient cannot receive it, collect the following information before contacting Support:
- The sender’s email address.
- The recipient’s email address.
- The approximate attachment size.
- Any error message or bounce-back notification.
- Screenshots (if available).
- The time the email was sent.
Related Articles
- Understanding Email Sending Restrictions
- Why Are My Emails Being Rejected?
- How to Reduce Email Attachment Sizes
- Understanding Email Sending Errors
- Monthly Bandwidth: Does Email Count Towards This with 1-grid?
FAQs
What is the maximum email size I can send?
Emails sent through MailChannels support a maximum total message size of 25 MB, including attachments.
Does the 25 MB limit include attachments?
Yes. The limit includes the email body, all attachments, and the additional encoding required during transmission.
Why did my email fail even though it was under 25 MB?
The recipient’s mail server may have a lower size limit than the sending server, or the message size may have increased due to email encoding.
Can I send multiple attachments?
Yes, provided the combined total message size does not exceed 25 MB.
Why do attachments become larger when sent?
Email attachments are encoded before transmission, which increases their overall size.
What’s the best way to send very large files?
For files larger than the supported email size, it’s generally better to upload them to a secure file-sharing service and send the recipient a download link.
Empowering Insight
Most email delivery issues involving large attachments can be avoided with a few simple checks before sending. By keeping your total message size below the supported limit and using file-sharing services for larger files, you can improve delivery success and ensure your recipients receive your emails without unnecessary delays.
Need Additional Support?
If you’ve worked through the steps in this guide and are still unable to send or receive large emails, we’re here to help.
Before you contact us so that our 1-grid Support team can help, gather the recommended information listed in the If This Didn’t Work section. Providing these details upfront will help us investigate the issue more efficiently and resolve it as quickly as possible