What is the File Size Limit of an Attachment to an SMS or an Email

SMS/phone carriers and email providers have attachment file size limitations to prevent deliverability issues and to make sure that their servers are not overloaded with hefty file sizes while millions of people around the world use their services to send SMS and Emails.


In this article:


SMS

LC Phone and Twilio support up to 10 attachments, as long as the total size of the message body text and all attachments is less than 5 MB.


Carriers also have limits. The average is 300kb-600kb and can go up to 3.5MB for tier 1 providers (AT&T/Verizon, etc.)


Here are the Carrier Attachment Size limits for some common US Carriers:

Common US Carrier attachment sizes

The file sizes above will generally be passed along to the wireless carriers. However, due to differences in handsets, file types, and transcoding, we recommend you send attachments no larger than 500KB to ensure the best chance of delivery.


These image file types are supported:

  • jpeg
  • png
  • gif

If you have your own Twilio account integrated with FG Funnels, ensure that your Twilio phone number is MMS enabled. You can also find more information on file types and size limits in MMS media messages in this article.


Please Note:

As of May 2021, there is an issue with Toll-Free MMS file size support; for toll free numbers, you must ensure that any attachments (including images) are 600kb or smaller.


Email


Mainly for security reasons, all email server providers limit the maximum email size that an email account can receive. Otherwise, if there would be no maximum email size limit, the email server would risk being bombarded with very large emails, causing it to cease working properly.


Some free email address providers also enforce commercial limitations on the email size: the free account gets a low maximum email size limit, but you can increase the maximum limit by upgrading to a paid account.


If you send an email that exceeds the maximum email size limit of the recipient’s email provider, your email will bounce and you will receive an email error back in your Conversations tab. Usually, you will receive one of the following error messages:

  • “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. The message was not sent; reduce the message size and try again”.

Both LC Mail and Mailgun support maximum messages size of 25MB.


Here are attachment sizes for different Email Providers.

Attachment sizes for different email providers


FAQs


Can I send mp4 files via SMS?

MP4 files are supported for sending as MMS attachments. If you attach an mp4 file, it should be sent as an MMS. However, MP4 files cannot be attached directly when sending SMS.


Can you bypass these maximum email size limits?

A simple answer would be: no, you can’t bypass these maximum size limits. However, there is a workaround:

You can upload the files-to-be-attached to cloud storage servers (like DropBox or Google Drive) and include the download link in your email.