You find emails with Attachments smaller than the allowed size: for the whole message or if you are also using Content Filtering Policies to set more especific limits to size.
You find the emails fired by: 'Unscannable' Virus Policy or 'Message Size Exceeded' restrictions.
This is working by design: The XLSX file type is primarily associated with 'Excel' by Microsoft Corporation. This is the new format for Microsoft Office documents. It is a combination of XML architecture and ZIP compression for size reduction (basically means that still carries compression after you unzip it). Microsoft Excel 2007 uses zip compression within is native xlsx file format. Since plain text can be compressed considerably, while the file size of the Excel document may only be 15 to 20 megabytes the actual size when uncompressed would actually be several hundred megabytes and also violate the container limits. Typically the Excel Doc is 10% of the uncompressed file size IE a 20mb file would be near 200mb Uncompressed.
Do one of the following: depending on your case.
1. 'Message Size Exceeded': Increment the Message Size Limits: Administration > Configuration > Host > SMTP > Adv Settings > Inbound/Outbound > Message Size in Bytes = Message (body) + Attachment. (Not only weighs the attachment but the whole message). Increment the value up to a few MBs.
2. 'Unscannable': Protocols > SMTP > Settings > Scanning > Increment the value for: Maximum individual file size when opened and Maximum accumulated file size when opened.
3. For issues with Content filtering policies based on the attachment size, Upgrade to SMG version 10.5.3
For Content filtering policies based on the attachment size, all SMG versions until 10.5.2 included are impacted.
NOTE: This behavior has changed from SMG 10.5.3 onwards. For further references please refer to the following Symantec KB article:
Imported Document ID: TECH171495
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