Cisco Cisco Email Security Appliance X1070 Fehlerbehebungsanleitung
Question:
Environment: Cisco Email Security Appliance (ESA), all versions of AsyncOS
You may observe that an email message with a binary attachment appears to be much larger in size when
viewed via the mail_logs compared to the size of the binary attachment. This is because binary files in
attachments are encoded before the email message is delivered to an MTA. The most popular are base64 and
uuencode. The goal of encoding is to accurately represent 8−bit characters within the 7−bit limitation of
SMTP.
viewed via the mail_logs compared to the size of the binary attachment. This is because binary files in
attachments are encoded before the email message is delivered to an MTA. The most popular are base64 and
uuencode. The goal of encoding is to accurately represent 8−bit characters within the 7−bit limitation of
SMTP.
Take base64 for example: Base64 encoding takes three bytes, each consisting of eight bits, and represents
them as four printable characters in the ASCII standard. Therefore a message that appears on an MTA as 100
bytes, is actually 75 bytes in binary format.
them as four printable characters in the ASCII standard. Therefore a message that appears on an MTA as 100
bytes, is actually 75 bytes in binary format.
Updated: Aug 12, 2014
Document ID: 118209