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Mail Shield

This Article Applies to:

  • Avast Business Hub


Mail Shield checks incoming and outgoing email messages for viruses and links to malicious websites. This only applies to messages handled by mail management software installed on your computer, such as MS Outlook. If you access your web-based email account via an internet browser, your devices are protected by other shields.

We do not recommend you install this component on a server OS that is also running Microsoft Exchange. The Exchange and Anti-spam components handle Exchange-level filtering and will conflict with this component.

Windows and macOS configuration options are mixed together in the policy settings for the various components.

Note that in Antivirus for macOS, the shields can only be disabled, not uninstalled. Therefore, if you uninstall Mail Shield from a policy, the service on macOS endpoints will only be disabled.

Main Settings Tab

Inbound mail: choose whether inbound (POP3, IMAP4) email is scanned

Outbound mail: choose whether outbound (SMTP) email is scanned

Newsgroup messages: choose whether newsgroup messages (NNTP) are scanned

Enable IPv6: (Business Hub and Cloud Console) for macOS systems; choose whether to scan devices using IPv6 or not

Scan secured connections: (Business Hub and Cloud Console) for macOS  systems; choose whether to scan emails sent or received over secure protocols or not

Report PUPs: (Business Hub and Cloud Console) for macOS systems; choose whether to report potentially unwanted programs (PUPs) or not

Mark mail headers: (Business Hub and Cloud Console) for macOS systems; choose whether to add a warning to the header of suspicious emails or not

Email attachments: (Business Hub and Cloud Console) for macOS systems; choose whether to remove suspicious email attachments before downloading emails or not

Behavior Tab

Configure notes added to emails or additional options for MS Outlook.

General: choose whether to insert notes into clean or infected messages, both incoming and outgoing, and/or to add a warning to the subject line of infected emails

MS Outlook only: choose whether to show splash screen, scan files when attaching to email, and/or to scan archived messages when opening (or just unread ones)

SSL Scanning Tab

Choose whether or not to scan SSL connections.

Actions Tab

Control what actions are taken by Avast when a virus, potentially unwanted program (PUP), unwanted tool, or suspicious file is detected.

Main Action/First action to try: Select the first action you want your Antivirus to take (for example, if it will first attempt to fix or quarantine the threat, or delete it immediately).

Notification Options: Choose whether to show notifications when Mail Shield takes action against a detected threat.

Processing of infected archives: Choose whether to only remove the packed file from the archive (and if that fails, do nothing), remove the packed file from the archive (and if that fails, remove the entire archive), or to remove the entire archive.

Packers Tab

Configure which archive (packer) files Antivirus should try to unpack during the scanning process. Unpacked files can be better analyzed for malware by Mail Shield. Unpacking a file is the same as extracting a file from an archive. Original archives, including the files contained within, remain intact when being processed by your Shield.

You can select All packers, or specific packer files from the extensive list by checking the boxes.

Sensitivity Tab

Adjust the sensitivity of the Antivirus scan for Mail Shield.

Heuristics Sensitivity: Heuristics enable Antivirus to detect unknown malware by analyzing code for commands that may indicate malicious intent. The default setting is Normal. With higher sensitivity, Antivirus is more likely to detect malware, but also more likely to make false-positive detections that incorrectly identify files as malware. Code emulations unpack and test suspected malware in an emulated environment where the file cannot cause damage to devices. Use code emulation is enabled by default

Sensitivity: Choose to test whole files, which will cause the scan to be slower but more extensive

PUP and suspicious files: Choose whether or not to scan for Potentially Unwanted Programs (PUPs)

For Antivirus versions 21.5 and newer, you can also choose whether to scan for potentially unwanted tools.

Report File Tab

Customize the content of the shield-specific scan report file, such as which items are included, the file name, and file type. The report is saved in C:\ProgramData\Avast Software\Avast\report (Windows 7 and higher).

Adding Mail Shield Exclusions (macOS Only)

If needed, you can add exclusions to the Mail Shield scans through the Antivirus Exclusions settings of a selected policy. This can speed up the scans and prevent false-positive detections.

For more information on standard and component-specific exclusions, see Configuring Antivirus Exclusions.