At LyteHosting, we enforce certain limits for email attachments to ensure optimal performance and compatibility. Please note that while our servers have these standards, the recipient’s email server may have different restrictions.
Attachment Size Limits by Hosting Plan
1. Shared and Reseller Hosting
Maximum Size: Approximately 20 MB
(This is based on the actual file size on your device.)
2. Windows Hosting
Maximum Size: Approximately 23 MB
(Based on the file’s local size before sending.)
3. Linux Dedicated, Windows Dedicated, and VPS Hosting
By default, these plans follow the same limits as Shared Hosting. However, since you have root access, you can adjust the maximum allowed attachment size.
(Remember, this doesn’t guarantee the recipient’s server will accept a larger file.)
While our Linux servers technically allow up to 50 MB for outgoing emails and our Windows servers allow 30 MB (including both the message body and attachments), various factors influence the success of sending large files:
Factors That Affect Attachment Delivery
1. MIME Encoding Increases File Size: Attachments are MIME-encoded for transmission, which inflates file size by around 40%.
- A 35 MB file becomes roughly 50 MB.
- A 23 MB file becomes approximately 30 MB.
2. Email Client Limitations: Each email application has its own size restrictions for sending attachments.
3. Recipient Server Limits: Different providers have different limits. For example:
- Hotmail – 10 MB
- Yahoo! – 25 MB
- Gmail – 50 MB
4. Recipient Email Client Restrictions: These may vary by email software and settings.
5. Recipient Mailbox Capacity: If the recipient’s inbox is full, your email will bounce.
6. Internet Service Provider Reliability: Some ISPs may time out or corrupt large file transfers.
You might send the same file to two people, one receives it while the other doesn’t. That’s typically due to rejection by the recipient’s email server because of file size limits.
Webmail Sending Limits
- RoundCube – Up to 20 MB
- SmarterMail – Up to 30 MB
Note: A file that's 35 MB on your device becomes roughly 50 MB once MIME-encoded. Similarly, a 23 MB file becomes about 30 MB after encoding.
SMTP & Email Clients (Sending)
You can send the largest file your email client allows, within LyteHosting’s SMTP limits:
- Shared/Reseller Hosting SMTP – Accepts up to 20 MB
- Windows Hosting SMTP – Accepts up to 30 MB
Popular Email Client Defaults:
- Outlook 2010 – 20 MB (can be adjusted in the Windows registry)
- Outlook 2007 – Subject to server limits
- Mozilla Thunderbird – Follows server-imposed restrictions
Common Recipient Email Limits
Here's how popular email services handle incoming attachments:
- Gmail / Google Mail – 50 MB
- Yahoo! Mail – 25 MB
- Hotmail / MSN / Windows Live – 10 MB
- Lycos Mail – Unlimited
- Excite Mail – 25 MB
- AOL Mail – 25 MB
Note: These figures are for reference only. Providers may change their policies at any time without notice.
Troubleshooting Tips
Q: Why does my email with an attachment fail to deliver or bounce back?
A: The most common reason is that the attachment exceeds the size limit. Make sure your file is under 23 MB to increase delivery success.
Q: Why are .exe or .src files blocked?
A: For security reasons, these file types are restricted unless compressed in a ZIP archive. This helps protect your inbox from viruses. This restriction cannot be disabled.
Q: My webmail allows 20 MB, but why can't I send a 50 MB file?
A: MIME encoding expands file size by around 40%. A 40 MB file becomes approximately 56 MB when sent, exceeding the 50 MB threshold.
Q: How can I send large files securely?
A:
- Upload the file to your LyteHosting website and send a secure link.
- For sensitive files, place them in a password-protected directory and share the login credentials via email.
