A user receives the message: 552-'Message size exceeds fixed maximum message size set by administrator' when sending an email with an attachment to a Symantec Mail Security for Domino with Premium Antispam Enabled
The option "Maximum Message Size" located in Antispam > Premium Antispam > SMTP Proxy has value below the affected message.
To increase the allowed message size follow the steps below:
NOTE: The message size is the body of the message plus attachment(s).
When setting limits in the Maximum message size in bytes field, please be aware that MIME encoding overhead on your mail client adds approximately 30% to the file size of an attachment in a message, depending on the type of attachment.
E.g. if the attachment is plain text, hardly any overhead is added, whereas if your attachment is a zip or exe file, the overhead is can be even more than 30%.
Also, Base64 encoding can add the same overhead (30% or more) to messages that only contain text in the message body.
Therefore if you want to send/receive attachments that are 6MB in size or smaller, you would need to set a 10000000 byte (10MB) limit in this configuration option.
If you want to send/receive attachments that are 10MB in size or smaller, you would need to set a 14000000 byte (14MB) limit in this configuration option.
The size limits apply to the size of the compressed file.
E.g.: If the decompressed size is over 10MB the mail will be accepted as long as the combined size of the compressed attachment, the message body and the Encoding Overhead is less than 10 MB.