I'm having the same problem as this thread. https://www.3cx.com/community/threads/mail-settings-not-working-after-15-5-upgrade.54328/ I'd add my issue there but it's been locked to further comments. Everything working fine for the last 8 months, including voicemail to email. Early this morning installed v15.5 Update 3 and by mid-morning numerous complaints from users that voicemail to email isn't working. I haven't changed email settings in 8 months as it was working and I didn't need to. Went in and tested and it errored out. Went into the Exchange server (Exchange 2010) and enabled TLS and it still doesn't work. Finally as a work around I have them going through a different email address via Office 365 and their hosted Exchange. That does work. However I fail to see the logic of it "not being 3cx's fault" as was stated by support in the other thread. You took something that worked and after an update it no longer worked. There was no warning or notice that email would need to be reconfigured after installing this update. You guys really need to stop trying to avoid blame when an update screws things up. It should have been in the release notes that there were changes to the email platform. It should not be a surprise to us after the fact. And for what it is worth I spent several hours trying to get it to work with TLS after the fact and never could get it working with Exchange 2010, only 2016. Needing to do a full 2 version upgrade to an Exchange server shouldn't be some random thing we are left to figure out. Had it been in the release notes I simply wouldn't have installed the update. If there is a way to configure Exchange 2010 to work with this release, then please publish the steps as I couldn't get it to work and clearly others have had the same issue. In the meantime I either need to keep routing their voicemail through a separate email server than the one this client has on site or I need to convince them to spend a few thousand dollars to upgrade to a newer version of Exchange. That shouldn't be something that is a surprise after an update.