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How to navigate the data limits on email

How to navigate the data limits on email


To navigate the data limits on emails effectively, start by familiarizing yourself with the attachment and total email size limits of popular email providers such as Gmail, Outlook, and Yahoo. Organizations can adopt targeted strategies to ensure that emails remain within size limits, improving deliverability and avoiding common size-related errors.

Why do email providers impose data limits?

From a performance perspective, limiting the size of emails ensures that the email system operates efficiently and remains responsive. Large emails can slow down server processing times, affecting the speed at which users send and receive messages. Regarding storage, email servers allocate a finite amount of space for each user. 

Setting limits on email sizes helps manage this space effectively, preventing servers from becoming overwhelmed by excessively large files. Security concerns also play a significant role; limiting email sizes helps mitigate the risk of denial-of-service (DoS) attacks, where attackers might attempt to overload the system by sending large volumes of oversized emails. 


What are the data limits for popular email providers?


  1. Attachment size limitGmail allows users to send attachments up to 25 MB in size per email.
  2. Total email size limit: The total size of the email, including all attachments, must not exceed 25 MB. If an attachment exceeds this limit, Gmail automatically uploads the file to Google Drive and inserts a link to the file within the email instead of attaching it directly.

Outlook/Office 365

  1. Attachment size limitOutlook permits attachments up to 20 MB for accounts with internet service providers (ISPs) and up to 25 MB for Office 365 subscribers.
  2. Total email size limit: Similar to the attachment size limit, the total email size limit mirrors the attachment restrictions, allowing up to 20 MB or 25 MB depending on the account type. For Office 365 users, Microsoft allows sending larger files by automatically uploading them to OneDrive, a similar approach to Gmail’s use of Google Drive.

Yahoo Mail

  1. Attachment size limit: Yahoo Mail has a maximum email attachment limit of 25 MB.
  2. Total email size limit: The total email size, including attachments, must not exceed 25 MB. Yahoo also offers an integration with Dropbox for sending larger files.

Additional Notes

  1. Email encoding overhead: Note that when attachments are encoded for email transmission (typically using Base64 encoding), they can increase in size by approximately 33%. Therefore, the actual limit for attachments you can send without hitting the cap may be lower than the stated limits once encoding is taken into account.
  2. Workarounds for large files: Most providers suggest using cloud storage services as a workaround for sending files larger than the attachment size limits. This approach involves uploading the large file to a cloud service and then sharing a link to the file in the email.

See also: What is data security?


How to navigate these data limitations 

Utilize secure cloud services

For sending files larger than the email limits, healthcare organizations can use secure cloud storage services that comply with healthcare regulations for data protection and privacy. Services like Google Drive, OneDrive, and Dropbox offer ways to share large files by providing a link in the email instead of attaching the file directly. 

See also: The underlying risks of using cloud storage


Compress files when appropriate

In some cases, compressing files can help stay within email size limits. However, compression should be used judiciously, especially with sensitive data, to ensure that the integrity and security of the information are not compromised. Encrypted zip files can be one method to both compress and secure the data, but recipients will need the means to decrypt them.


Implement email encryption

When sending sensitive healthcare information within the constraints of email size limits, encryption is a must to protect patient data. Many email providers offer encryption services that comply with healthcare standards. If the email system does not natively support adequate encryption, third-party encryption services that integrate with email clients can be a viable solution.


Educate staff on email best practices

Healthcare organizations should educate their staff on the best practices for managing email communications, including understanding data limits, using cloud services responsibly, and ensuring the security of patient information. Training should cover the necessity of data minimization in emails, choosing appropriate file formats that balance quality and size, and the procedures for sending large files securely.


Use specialized healthcare communication tools

Consider adopting specialized communication tools designed for healthcare environments such as HIPAA compliant email services like Paubox. These tools often offer secure messaging capabilities that can handle large files, are tailored to the needs of healthcare professionals, and are built to comply with healthcare regulations. They can be a more efficient and secure alternative to traditional email for many healthcare communication needs.



How can I check the data limits of my email provider?

You can typically find the data limits of your email provider in their help or support sections. Providers like Gmail, Outlook, and Yahoo explicitly list their attachment and total email size limits on their websites.


What happens if I exceed these limits?

If you exceed your email provider’s data limits, your email may fail to send, and you'll likely receive an error message. If you're sending an email, the message may be rejected by the recipient's email server if it exceeds their incoming limits.


Can embedding images in emails affect data limits?

Yes, embedding images directly into an email can significantly increase its size. Consider hosting images externally and linking to them within your email to save space.

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