Knowledgebase: outmail
What are the outmail message size limits

Problem:

What are the outmail message size limits?
What is a max size of a message?

Solution:

outMail message size limit is set to 26Mb (MIME encode).

So what does that mean to an actual message size (to save me working out the MIME encoded size)?

Typically MIME encoding a message adds approx 33% to the real size of the message.  So a 26Mb MIME encoded message would be a real message of 20.1Mb in size.

Remember the MIME Message size will include the combined size of the headers, message body and all the attachments.

FAQ:

Q - Can the message limit be increased?
A - Yes but No. We could change the message limit size however if the receiving server has a smaller size limit the message would fail.

Q - Why 26Mb?
A - Original size limits were defined in the SMTP RFC Standards however when it became possible to attach multimedia to emails the attachment size grew, so most ISP's decided on 25Mb for their own message limits.

Q - My Exchange server won't let me send emails that large.
A - Check your message limits on the Send Connector it could be set to 10Mb by default.

Q - What are other ISPs message size limits?
A - Google Mail (GMail), BT, Yahoo Mail, AOL, VirginMedia are set to 25Mb. Outlook.com and Hotmail are set to 10Mb.

Additional Information

For more information on message size limits, minimums and restrictions please refer to SMTP RFC (RFC 2821), http://www.ietf.org/rfc/rfc2821.txt.

 

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