Suddenly my Outlook 2010 and eMClient email programs can only intermittently connect to my POP3 mailbox to download email. After assuming an ISP and/or router issue was the cause initially I’ve discovered it’s Avast Free Business Security that’s to blame. If I disable the Mail component then Outlook and eMClient both work perfectly. It’s a very simple POP3 server, uses the standard port of 110 and doesn’t use SSL encryption, just plain username/password to gain access. I’m presuming Avast 17.7.2526 is to blame as it only started recently. I’ve uninstalled and re-installed to no avail. Running Windows 10 Pro v1709 64-bit.
Telnet to my POP3 server on port 110 with Avast enabled doesn’t work, but it does if Avast is temporarily disabled.
Sounds odd. Is the same thing happening on other PCs in your network? I’d guess if it was working with a previous version, but that version no longer works either, then probably a conflict with something else that changed in your environment (eg the Creator’s Update broke something). Did you use https://www.avast.com/uninstall-utility to uninstall? Might be worth running it to clear out any bits left behind before installing again.