SQL Server database backup file (.bak ) file gets corrupted

I have been working on a SQL Server database designing since long now and I have observed that when a .bak file is mailed or kept and downloaded from ftp site, it gets corrupted.

When I try to restore, it gives me 3013 error code with messsage:

“Backup or restore operation terminating abnormally.

I tried RESTORE VERIFYONLY FROM DISK='C:abc.bak' as well but it says

VERIFY DATABASE is terminating abnormally.

Any idea why this is happening and also, is there a better way to move the database file from one server to another (I do not have the access to source server)

Thanks in advance.

Answer

For FTP make sure that you use binary mode. Did you try to send plain attachment to yourself and compare the results with the files from sent and received email?