Attachment too big error message specifies different size between clients

When you try to attach a file above the limit the client will warn with a message such as “the email message cannot be sent because it exceeds the 35MB outgoing message size limit”

I have noted windows mail and owa will say 33MB, Windows Outlook client will 35MB and Mac can be different again using the same email account. The actual limit is 34MB.

I need an actual explanation/reason why this is and why windows mail/outlook web would state the limit is 33MB and Outlook windows client would state 35MB when trying to attach a file over the limit but have not had any luck so far.

This is so I can explain why different numbers are displayed depending on client when the actual limit set is 34MB as part of some research I am doing.

Any insight would be appreciated.

The email client likely acts as a gatekeeper in this case and determines when to stop you from sending an attachment. The attachment limit imposed by each email client would naturally be implementation dependent.

Perhaps some of the variation might be attributed to how each email client calculates a megabyte. For instance, if you have a file that is 35,000,000 bytes, an email client using base 2 would treat the file as being ~33.38 MiB while one using base 10 would find that the file is 35 MB. In summary, the difference between mebibytes and megabytes (or JEDEC megabytes vs metric megabytes) might be part of the issue :smiley:

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