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Problems sending large attachments through Outlook

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Problems sending large attachments through Outlook

The sending of emails with large attachments using Outlook is not working well with our new U-Verse service.  We switched from Cox as our Internet provider to ATT U-Verse 9 days ago.  Everyting -- phone, television, and basic email are working well-- except this email issue of attachments.  Although we are supposed to have a maximum of 25 MG per email, we cannot send anything beyond about 18 MBs.  To do that I have to disable the virus scan for emails.  Sending large emails of this size was never a problem with our Cox service and the maximum email size was 20MB.  Has anyone had this problem?  Any solutions to recommend?  I spent 2 hours on the phone with tech support and they could not help me; they suspect the problem has something to do with Outlook settings.  I was referred to the ATT fee-based support or calling Microsoft.

 

Thanks.

Pauline

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Expert

Re: Problems sending large attachments through Outlook

E-mail file attachments are typically encoded with a method called base64.  Base64 expands the size of a file by approximately 1/3.

 

If 25 MB is the AT&T limit, then that is for the base64 encoded e-mail.  This limits the unencoded file to 3/4 * 25 MB = ~ 18.75 MB.  There is another tiny amount reserved for overhead, so 18 MB is approximately the limit.

 

You can send the file in multiple pieces if you want by using a zip program (like WinZip or 7Zip) and specifying that the .zip archive be split into 17 MB pieces.  Then send each one as a separate e-mail.  The person on the other end can then use the same .zip program to reassemble them.

 

Message 2 of 3
Contributor

Re: Problems sending large attachments through Outlook

Thanks for the suggestions.  I was afraid that the amount I was sending plus the amount needed for encoding was pushing me over the limit.  I will keep in mind your suggestions for sending multiple emails using a zip program.  Thanks again.

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