Gmail and Yahoo (SSL encryption) emails fail to send and just hang in Outbox of Outlook.
Exactly the same as SpeeDyLOCO I was having problems with my brand new Dell Inspiron 7580 and a brand new installation of Outlook (2016? - the latest version anyway). Whilst it would send emails from my POP3 accounts with BTInternet.com it wouldn't send any from Gmail or Yahoo. The Outlook test messages worked okay so it wasn't the password (although I switched off 2 factor authentication just in case although I knew it wasn't that as the same accounts with exactly the same settings worked fine still on my old Samsung laptop with the same version of Outlook). The messages from Gmail and Yahoo would just hang in the Outbox forever. Dell support were as much use as a chocolate teapot and just referred me to PC World whom I'd bought the thing from. PC World support were okay at first as I'd taken out the £8 per month support plan to help out the sales guy but cancelled it three days later. They didn't want to know after that and just told me to do a factory re-set. Muppets! I'd already done a LOT of searching the Internet for answers all to no avail, so then I got on to Microsoft Office support. One of their tech guys took remote control of my Dell and was mystified. He spent about 90 minutes and couldn't work it out. He upgraded my case to 'level 2' support and said they'd call me 'on Wednesday'. They didn't. A call did come the following Wednesday but only rang 5 times and they hung up before I could pick up. Aaaargh! And you cannot contact MS level 2 support yourself in any way. I tried back with the online chat at level 1 and as soon as they found out that it was escalated to level 2 already they didn't want to know. Promised that they'd call me back later the same day. Nothing. So after another 3 weeks or so, I got back onto another level 1 tech by online chat. He again took remote control and I didn't tell him it was already with level 2, I wanted him to have a try at least. And, you know what... he managed, after about an hour, to isolate it. He went through all the previous stuff like a new Outlook profile and, this time a new Windows profile. Neither worked but then he did a clean boot with only MS services running and EUREKA! the emails started sending. Which just left me to keep turning on the services that had been set not to load one by one until I found the offender. Actually I turned on half at a time and got there fairly quickly. And of course, the offender was SmartByte. I tried to update it... the Dell support site where you update your drivers had a new version of SmartByte with a date of just a few days ago on it, but on installing it, it was actually just the same version anyway. Another expletive from my mouth. Anyway, I uninstalled it with Revo Uninstaller Pro (although that's probably not necessary as it didn't find anything left over) but there was still SmartByte left in the start menu alphabetical list which I could right click on and get an uninstall button. I guess from the MS app store rather than a whole program. And then there were a couple of things in Location: C:\ProgramData\Dell\ that I searched for 'smartbyte' and deleted. And now everything works fine. I'm not sure if SmartByte will try to come back and I'm not interested in trying to see if all the other Dell software is up to date and compatible with it. I've never had a computer with SmartByte before and I've never missed it. Don't think I will now.