Postfix message_size_limit

[vpx]

In the Postfix plugin the default value is 51200000 Bytes.

I know it follows the convention of the original documentation.

message_size_limit
(I linked via Wayback Machine as I don't know why the Postfix site is currently offline)

But does anybody know why that is?

I mean it is calculated as 50x1024x1000 = 51200000 Bytes.

Shouldn't it either be 50x1024x1024 = 52.428.800 Bytes or 50x1000x1000 = 50.000.000 Bytes?

I know the diference between KiB and KB, MiB and MB etc. but why is it a mixed case here?

[Patrick M. Hausen]

I read that as 512 x 100.000. One power of two, one power of ten.

[vpx23]

OK, I found the explanation on Wikipedia:

The IBM System 360 and the related disk and tape systems set the byte at 8 bits and documented capacities in decimal units.[38] The early 8-, 5.25- and 3.5-inch floppies gave capacities in multiples of 1024, using "KB" rather than the more accurate "KiB". The later, larger, 8-, 5.25- and 3.5-inch floppies gave capacities in a hybrid notation, i.e., multiples of 1024,000, using "KB" = 1024 B and "MB" = 1024,000 B. Early 5.25-inch disks used decimal[dubious – discuss] even though they used 128-byte and 256-byte sectors.[39] Hard disks used mostly 256-byte and then 512-byte before 4096-byte blocks became standard.[40]

Source

Being an IBM product it makes sense that this hybrid notation was used in Postfix.