Thunderbird Connects but times out

Thanks to all of you for the VPN hint. I discovered that it worked on my side too. I also realized the Xfinity email web app didn't work until I tried it over a VPN connection. My desktop is hardwired into a switch as is a laptop I used for testing. The laptop worked fine whether without the need for being on a vpn.

Using this information I reached out to Comcast support. I have spent several days working on this issue. Once I tried the vpn this afternoon I reached out to Comcast support again suspecting that my main computer had in fact been blacklisted although I don't yet know why or how. That being said I was on the phone for 5 hours, spoke to 10 people and was hung-up on twice.

In the end I made it to the Security Assurance Department who is working on an investigation and are supposed to provide email accessand an explanation within 24 hours. I have a Ticket number now and that should help a great deal.

So my suggestion to the rest of you is call into support and try to get to the Security Assurance Department as quickly as you can so they can work on your issue. Its ironic that most of us experienced this problem on Tuesday with Thunderbird. If you call support, particularly if you have had success with a VPN, I would not start with my email isn't working, but instead ask why your email client has been "Blacklisted". Hope some of you find this useful. Good luck!

Thanks sam-williams!  Please update this thread when you hear more crom comcast.

@TS2430 @ferriro1 @whichfinger @sam-williams 
I apologize for the issue(s) you are experiencing. Can you please PM(Private Message) me the following details so we can take a further look into this:

IP address (using whatsmyip) of the time the issue occurs:
Thunderbird Client Version:
Thunderbird port configurations (465/587):
Best contact phone number (should we need to troubleshoot over the phone): 

@sbrozell just to confirm, updating your email client did resolve the issue for you? or are you still experiencing problems? if so, please provide similarly the above information to me in a Private Message. 

To open up a little background into the issue - enabling VPN is a unique resolution to the issue that has never worked thus far. It has been the opposite due to VPNs being hotspots for abusive activity over the internet. In a few of the posts there is mention that other users on the network using their devices with similar email programs are not having issues, which would rule out an IP block or an issue with the network overall and specifically point towards a device-related issue. @whichfinger mentions being able to access via outlook, but not via thunderbird, which narrows it further down to being likely an issue within tunderbird. I'd appreciate the details mentioned above to further look into it and confirm what we are seeing on our side of the authentication process because interestingly, each of you had a series of authentication failures recently, likely from the third party email clients. Once i have received the information mentioned above, i'd be able to start looking further into the issue and reach out with further updates once i have them.

To note, with the limited information available, our logs do indicate that an attempt was made to contact our server in a few of the instances, but when it came to requesting authentication information - the email client or whatever was attempting to access the email simply did not provide the information to our server and timed out the connection. (imagine checking out at a store, cashier tells you the total, you stare at the cashier for a minute and then leave the store without your groceries and paying)

@ComcastCSAEmailmy email worked when I went to bed and didn't when I woke. I have demonstrated to the 10-15 people I've spoken to online where the problems were, but no one wanted to listen or offer anything but apologies. My email has now been down for 8 days. There have been two internally tickets created on my behalf, but neither have resulted in any serious escalation or resolution. I have spent several hours talking to people on the phone and dealing with the @ComcastCares twitter account and no forward progress has been made. It appears that the problem is rocket-science and there is no one on your staff that understand it. When a person relies on a service and then it stops while he is sleeping its pattenly ridiculous to suggest that my Thunderbird configuration is wrong particulaly since that configuration has worked for years,,, Unless Comcast changed something that negatively impacted Thunderbird users and they didn't communicate the change. I really can't believe this. Your company has embarassed itself when paying customers have outages on supported software and no one can help resolve the problem.

My email stopped working at the same time with the same symptoms. I run Outlook 2016 though. I was finally able to diagnose that it was due to not having IPv6 enabled on my Ethernet card. Once I checked that box it started working again. If I uncheck it, it goes back to not working again. To me it seems like something is wrong in the IPv4 path to imap.comcast.net. I have communicated with support about the issue but they do not see an issues so are not investigating further.

Give me a thumbs up if this was your issue as well.

@ComcastCSAEmail  I have the exact same issue but I don't see a way to private message you.  I've like to get this resolved as it's been several days.

ST_94, iPv6 is already checked on mine.

This fixed the problem for me, I found it on a different thread:

I have windows 10.

I verified that the connection was failing using openssl and wireshark.  I can send the wireshark file if anyone wants to analyze it.

I checked and changed MTU through the windows 10 power shell.  To check MTU and determine the LAN name (IN POWERSHELL):

netsh int ipv4 show subinterface

MTU MediaSenseState Bytes In Bytes Out Interface
------ --------------- --------- --------- -------------
4294967295 1 0 1694890 Loopback Pseudo-Interface 1
1504 1 1089714654 35479773 Local Area Connection
1504 5 0 0 Local Area Connection 2
1500 5 0 0 Local Area Connection 6

This showed MTU was set to 1504 on my active LAN connection which was "Local Area Connection".

I then executed the following command (in power shell)

netsh int ipv4 set subinterface "Local Area Connection" mtu=1500 store=persistent

tridecaphi, I don't know about the others posting here, but I am a long ways from a Windows power user and have no idea what you just did or how to go about duplicating it or undoing it if it doesn't work. ☹️

@whichfinger 

Let me try and walk you through it.  This is assuming you have windows 10.

In the bottom left hand corner of your screen you should see a magnifying glass and the words "Type here to search."  Click in that window and type "powershell."

You will see "Windows PowerShell" app pop up and on the right side below the app name, there is an option that says, "Run as Administrator."  I don't know that you have to use this option, but I did and I prefer to run powershell as administrator.

When you select "Run as Administrator" it pops up a window that asks you if you want to run powershell, click Yes.  The app has a blue background and shows you a command prompt.  Copy the line below (use your mouse and click and drag so the whole thing is highlighted, then right mouse click and select copy):
netsh int ipv4 set subinterface "Local Area Connection" mtu=1500 store=persistent

Once you have it copied, click the powershell window and make sure you see the flashing underscore "_ " and then right mouse click in the window to paste that text.  Once you verified there are no copy paste errors and the text in the window matches the line above, press enter.  That should return a result that simply says "OK."  That's it, check your email and see if it works, it should.

My MTU was set to Jumbo frame size. Once I bumped it down to 1500 I was able to turn off IPv6 and have it work. I wonder why the system was so sensitive to packet fragmentation all of the sudden?

tridecaphi,

Thanks for the effort, but I'm running Windows 7 Home Premium. ¯\_(ツ)_/¯

I tried the powershell fix and it didn't work for me, so far the vpn is the only way I am able to receive email from my comcast email address.

Here is a good link on how to change your MTU size on Windows 7 & 8.

https://support.zen.co.uk/kb/Knowledgebase/Changing-the-MTU-size-in-Windows-Vista-7-or-8