What is MlfHook.dll?

MlfHook.dll is a Windows DLL file. DLL is the abbreviation for Dynamic Link Library. DLL files are needed by programs or web browser extensions, because they contain program code, data, and resources. The following information can help you determine if MlfHook.dll is a Windows system file or if it belongs to an application that you can trust.

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MlfHook.dll file information

The process known as Spam Filter Hook belongs to software ZoneAlarm Extreme Security or ZoneAlarm Security Suite or ZoneAlarm Internet Security Suite by SonicWALL (

Description: MlfHook.dll is not essential for the Windows OS and causes relatively few problems. The MlfHook.dll file is located in a subfolder of "C:\Program Files (x86)" (e.g. C:\Program Files (x86)\CheckPoint\ZoneAlarm\MailFrontier\ or C:\Program Files (x86)\Zone Labs\ZoneAlarm\MailFrontier\). Known file sizes on Windows 10/8/7/XP are 13,120 bytes (64% of all occurrences) or 13,072 bytes. 
A .dll file (Dynamic Link Library) is a special type of Windows program containing functions that other programs can call. This .dll file can be injected to all running processes and can change or manipulate their behavior. There is no description of the program. The program has no visible window. There is no detailed description of this service. It can change the behavior of other programs or manipulate other programs. The file is not a Windows system file. The file has a digital signature. MlfHook.dll is a Verisign signed file. MlfHook.dll is able to record keyboard and mouse inputs. MlfHook.dll appears to be a compressed file. Therefore the technical security rating is 53% dangerous, but you should also take into account the user reviews.

Uninstalling this variant: You could remove the entire program ZoneAlarm Extreme Security or ZoneAlarm Security Suite using Windows Control Panel.

Recommended: Identify MlfHook.dll related errors

Important: Some malware camouflages itself as MlfHook.dll, particularly when located in the C:\Windows or C:\Windows\System32 folder. Therefore, you should check the MlfHook.dll process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


User Comments

Part of the ZoneAlarm SPAM mail filter
  John New York   (further information)
Part of the new spam filter in ZoneAlarm Security Suite 7. Safe
  Pat EM  
MailFrontier Desktop is an anti-spam and anti-phishing solution that filters and blocks unwanted spammed email messages.
  Shaynenhoose   (further information)
This is a component of MailFrontier Desktop. MailFrontier Desktop is an anti-spam and anti-phishing solution that filters and blocks unwanted spammed email messages. The program recognizes messages from the friend's list and messages from spammers through the automatic set-up. Messages missed by the program's filter can also be manually added to a block list.
  Buzz   (further information)
not dangerous
  pv   (further information)
part of ZoneAlarm, called "MailFrontier Desktop". This anti-spam and anti-phishing component filters and blocks unwanted spam emails.
Zonealarm's mail checker
Spam filter hook for Zone Alarm
  Knight of Toilets  
This is a part of ZoneAlarm

Rating chart

Summary: Average user rating of MlfHook.dll: based on 14 votes with 9 user comments. 12 users think MlfHook.dll is essential for Windows or an installed application. One user thinks it's probably harmless. One user suspects danger. One user is not sure about it.

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Best practices for resolving MlfHook issues

A clean and tidy computer is the key requirement for avoiding problems with MlfHook. This means running a scan for malware, cleaning your hard drive using 1cleanmgr and 2sfc /scannow, 3uninstalling programs that you no longer need, checking for Autostart programs (using 4msconfig) and enabling Windows' 5Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the 6resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the 7DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the MlfHook.dll process on your computer, the following programs have proven to be helpful: ASecurity Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. BMalwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

MlfHook.dll [all]