SMTP Blocking My IPv4

@Palmetto_Bug 

I cannot send emails through my comcast accounts. (Most of the time.) After days of working on this, including calls with Customer Service reps, I've come to the conclusion that Comcast's SMTP server is blocking my IPv4 address when using a third party email program (eM Client). If I use my laptop with my phone modem or through VPN everything works fine. If I plug my laptop directly into my cable modem (BTW, my ISP is Spectrum) a new IP address is assigned and everything is good. Of course, when I plug my router back into the cable modem the original IP address comes back and no outgoing mail. (Until around 8:00 PM. Then it seems to work for a little while.)

I have checked the the IMAP & SMTP settings and passwords. Also, the same behavior occurs if I use my Android phone over my Wi-Fi network. (It works fine if I force it into data mode over the phone network.)

How do I get my IP address off of the "naughty list"?

When was the last time you logged in to the Xfinity Connect website?

... Comcast's SMTP server is blocking my IPv4 address when using a third party email program ...

Some general information that may apply: https://forums.xfinity.com/conversations/email-and-web-browsing/smpt-server-not-connecting-how-to-get-help/629adf5d382dc22d0f76fc28?commentId=62a7557c382dc22d0f7746c7

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

Thanks for responding BruceW.

I reviewed that thread (and many others) before posting and checked my IP number against the  publicly available "block" lists. It only shows up on the generic lists that all dynamically assigned addresses are on. (Including the temporary IP that I got when directly hooking my PC to the cable router.) 

I also doubt that this is the issue as I can send emails after approximately 8:00 PM until sometime the next morning. If my IP address was on a "Spammer Hot List", I wouldn't think that Comcast would allow spamming at night. :<)

I'm back to a Comcast block of my IP address and how to get it cleared.

... I also doubt that this is the issue as I can send emails after approximately 8:00 PM until sometime the next morning. If my IP address was on a "Spammer Hot List", I wouldn't think that Comcast would allow spamming at night. :<)

Blocks are dropped periodically. Any chance you have a program, app, or device that is attempting to send email but repeatedly failing authentication? Employee @XfinityCSAEmail describes that scenario in https://forums.xfinity.com/conversations/email/cannot-send-email-0x800ccc0f-connection-to-server-interrupted-or-0x800ccc67-esmtp-server-temporarily-not-available-message/61b28270f06968168603033a?commentId=61b7a0b5f069681686037267&page=2, https://forums.xfinity.com/conversations/email/cannot-send-email-0x800ccc0f-connection-to-server-interrupted-or-0x800ccc67-esmtp-server-temporarily-not-available-message/61b28270f06968168603033a?commentId=61c38fb7af4f9801ee5e85dd and elsewhere.

I have checked authentication. Using my phone as a modem I logged all of the account activity and each of the email accounts are properly logging in, syncing and downloading new messages. I also checked on the phone itself, my backup phone and my tablet. 

Good morning,

Checking our logs I am seeing a lot of failed authentication coming from Amazon AWS IP spaces. Do you by chance have some kind of other device and/or service logging into your email address? I can see that it has a internal network IP designation of 10.252.2.158.

Thank you very much for looking into this.

Everything on my home network begins with "192.x.x.x". I am not home right now, so I can't try this address to see what happens. Do we have any idea when this started? 

Other than a laptop, tablet and phone, I have the usual array of IOT on my home network. Is there any chance that you can identify a manufacturer or MAC for the device (if that is what it is).

The only "Amazon" relationship that I can think of is our Ecobee thermostat, but we've had that for years.

Good afternoon,

Unfortunately the logs are retained for 30 days and its thousands to millions of lines of history logs so it would be a needle in a haystack on my end to figure out when it exactly started, usually its safe to correlate the start of when you noticed issues to be the time the authentication started failing. You are correct, an IOT device that connects to your emails for notifications could be a source of the issue as well. Unfortunately when it comes to technology its similar to the wheel, you can use it for thousands of years, but sometimes they still break. Granted its a bit more complicated for modern technology, but anything from a sudden loss in connection to a power outage could cause an IOT device to lose its settings and cause issues(not to exclude any firmware and/or software updates gone wrong). To add, we do not track or log MAC addresses for authentication to our mail servers(due to privacy reasons). Manufacturer ID is commonly tied to MAC so I would be unable to get that information for you either. The information on the traffic originating from an AWS cloud is the best detailed information I can provide. I did a bit more digging and I'm not sure if it helps, but I was able to find prior successful email transmission from the same source network and they do not appear to be generic IOT notifications. Looks like a normal correspondence with some of the emails marked as "FW" for forwarded or "RE" for reply emails. Do you by chance use any kind of email client or VPN service that could be routing your traffic through AWS(Amazon Web Services).

Thanks for you patience and education. I am learning a lot. During the last few days I started using Norton's VPN in order to send emails. That might be the recent AWS relationship. However, that was after the SMTP block.

Since I have not been home for two days and the home equipment is shut down, would it be possible to check to see if the authentication issue has been continuing during this time? If not, that might indicate that the the problem is coming from one of those devices.

FYI I have responded to StephanieT's Direct Message request above.

That's great news!

As I mentioned, I am out of town and using different hardware. Before leaving, I turned off the PCs and left on the IOT hardware. No failures over the weekend really narrows this down.

This weekend I am using a Windows tablet that only is used "on the road". Email was working fine, but I did notice a error in the email log file. I didn't write it down, but it something like " NotSupportedException: Collection was of a fixed size". I tried to do some research, but everything that came back was related to array errors.

Since I had some downtime (I can only spend so much time in 90+ degrees), I copied the Sent file to my tablet and deleted it from IMAP. Then I added back a portion at a time. The error did not return.

With a little luck, maybe this will resolve the issues from home as well. I'll find out tomorrow.

I think that we have it! When I fired up the home PC early this morning the SMTP errors were back. Following my test with the "Travel Tablet", I deleted some of the "Sent" files. This time I started by size, deleting everything over 7MB.

It's been up for several hours with no errors and no blocking.

I did check and Norton's VPN is using AWS, so that was the AWS connection. (I have been using my ISP without a VPN today.)

Thanks again for your help and patience!

My Outlook and Windows email apps have stopped working with my Comcast email.  The troubleshoot information said I need to check the security checkmark to allow it to work with 3rd party apps.  However nothing is working.  I am not getting emails on either of these applications