Can't retrieve email via mobile data

[Nil]

On my Android phone I've been unable to retrieve email for the past
couple of weeks or more, using my preferred IMAP client, Blue Mail or
K9 Mail. I am able to send email. I can get to webmail on a web
browser. I can get email when connected via WiFi. The error message I
get is:

Error - Sync failed, your username or password may be incorrect (3010)
Email server returned: "NO, [ALERT], Temporarily blacklisted IP Address
- try again later."

I'm sure the UID/password is correct, since I haven't changed it
lately. I assume my IP address changes every time I make a mobile data
connection, so that error message seems unlikely or misleading. My
server settings are those recommended by Comcast (server:
imap.comcast.net, Security: SSL/TLS, Port: 993.)

A couple of days ago I thought I had discovered a workaround: changing
my User ID from my full Comcast email to just the prefix, eliminating
the "@comcast.net" bit. This actually worked for about half a day, then
I started getting the same error message.

Has anybody else seen this, can anyone explain what's going on, and/or
can anyone suggest a workaround or fix?

[VanguardLH]

Post by Nil
On my Android phone I've been unable to retrieve email for the past
couple of weeks or more, using my preferred IMAP client, Blue Mail or
K9 Mail. I am able to send email. I can get to webmail on a web
browser. I can get email when connected via WiFi. The error message I
Error - Sync failed, your username or password may be incorrect (3010)
Email server returned: "NO, [ALERT], Temporarily blacklisted IP Address
- try again later."
I'm sure the UID/password is correct, since I haven't changed it
lately. I assume my IP address changes every time I make a mobile data
connection, so that error message seems unlikely or misleading. My
imap.comcast.net, Security: SSL/TLS, Port: 993.)
A couple of days ago I thought I had discovered a workaround: changing
my User ID from my full Comcast email to just the prefix, eliminating
I started getting the same error message.
Has anybody else seen this, can anyone explain what's going on, and/or
can anyone suggest a workaround or fix?

You probably are not getting a new IP address every time you use the
local e-mail client on your smartphone. You could use one of the web
sites that will report your IP address to see if it is changing or not.

http://postmaster.comcast.net/block-removal-request.html
http://www.myipaddress.com/show-my-ip-address/
Or Google on "my IP address" and Google will report it.

The site (Comcast's IMAP server) has an IP address blacklisted. You
currently have that IP address -- or your cellular provider's data host
does. Alas, the error message does not report what Comcast's IMAP
server saw as your IP address for the mail session your client attempted
to establish. Was it for your phone or for your cellular provider?

http://postmaster.comcast.net/block-removal-request.html

I'd first check what was your actual IP address at the time your e-mail
client gets an error about your phone getting blacklisted. See if you
really have a changing IP address or if it is constant. If your own IP
address is changing, it is possible Comcast has blacklisted your
cellular provider. As you move around, your phone's IP address may
change (with its connection to your cellular provider's host or node)
but not that for your cellular provider which is actually making the
connection to Comcast.

https://www.pcworld.com/article/2955112/your-mobile-ip-address-its-safety-is-one-thing-its-privacy-is-another.html

Because of the internal working of your cellular provider's data
network, I'm not sure if what's-my-IP sites are going to show the IP
address of your phone or that of your cellular provider's data host.
Those that report what IP address connected to them using the network
packets will see the WAN-side IP address of your router or, for a cell
phone, the NAT address of the cellular provider's host. For sites that
use Javascript within their web page, they can query the device to have
it report what is its local IP address. When I look at Settings ->
General -> About Phone -> Network settings, 4 IP addresses are listed
for my phone (but not which one is for which type of connection from my
phone - wifi, cellular data, Bluetooth, something else). Only 1 is
reported by the what's my IP sites that I tested.

There have been times when an ISP or e-mail provider has blacklisted a
huge e-mail service, like Microsoft blacklisting Yahoo, so Yahoo senders
cannot reach Microsoft recipients. You would think e-mail providers
would not blacklist (have a whitelist that overrides their anti-spam
blacklisting) the other major or well-known good e-mail sources but it
has happened. You could try to chat with Comcast to report they are
blacklisting your cellular provider's data service. You could chat with
your cellular provider to report they are getting blacklisted by
Comcast. With only a cellular data connection, I doubt Comcast has your
phone's local IP address blacklisted. More likely Comcast blacklisted
your cellular provider's data host (as that would be the source of the
connection to Comcast).

[Allodoxaphobia]

Post by VanguardLH

Post by Nil
Error - Sync failed, your username or password may be incorrect (3010)
Email server returned: "NO, [ALERT], Temporarily blacklisted IP Address
- try again later."

http://postmaster.comcast.net/block-removal-request.html
I'd first check what was your actual IP address at the time your e-mail
client gets an error about your phone getting blacklisted. See if you
really have a changing IP address or if it is constant. If your own IP
address is changing, it is possible Comcast has blacklisted your
cellular provider.

So, to find out:

https://www.google.com/search?q=whats+my+ip%3F

[Nil]

Post by VanguardLH

Post by Nil
On my Android phone I've been unable to retrieve email for the
past couple of weeks or more, using my preferred IMAP client,
Blue Mail or K9 Mail. I am able to send email. I can get to
webmail on a web browser. I can get email when connected via
Error - Sync failed, your username or password may be incorrect
(3010) Email server returned: "NO, [ALERT], Temporarily
blacklisted IP Address - try again later."
I'm sure the UID/password is correct, since I haven't changed it
lately. I assume my IP address changes every time I make a mobile
data connection, so that error message seems unlikely or
misleading. My server settings are those recommended by Comcast
(server: imap.comcast.net, Security: SSL/TLS, Port: 993.)
changing my User ID from my full Comcast email to just the
for about half a day, then I started getting the same error
message.
Has anybody else seen this, can anyone explain what's going on,
and/or can anyone suggest a workaround or fix?

You probably are not getting a new IP address every time you use
the local e-mail client on your smartphone. You could use one of
the web sites that will report your IP address to see if it is
changing or not.
http://postmaster.comcast.net/block-removal-request.html
http://www.myipaddress.com/show-my-ip-address/
Or Google on "my IP address" and Google will report it.
The site (Comcast's IMAP server) has an IP address blacklisted.
You currently have that IP address -- or your cellular provider's
data host does. Alas, the error message does not report what
Comcast's IMAP server saw as your IP address for the mail session
your client attempted to establish. Was it for your phone or for
your cellular provider?
http://postmaster.comcast.net/block-removal-request.html
I'd first check what was your actual IP address at the time your
e-mail client gets an error about your phone getting blacklisted.
See if you really have a changing IP address or if it is constant.
If your own IP address is changing, it is possible Comcast has
blacklisted your cellular provider. As you move around, your
phone's IP address may change (with its connection to your
cellular provider's host or node) but not that for your cellular
provider which is actually making the connection to Comcast.
https://www.pcworld.com/article/2955112/your-mobile-ip-address-its-
safety-is-one-thing-its-privacy-is-another.html
Because of the internal working of your cellular provider's data
network, I'm not sure if what's-my-IP sites are going to show the
IP address of your phone or that of your cellular provider's data
host. Those that report what IP address connected to them using
the network packets will see the WAN-side IP address of your
router or, for a cell phone, the NAT address of the cellular
provider's host. For sites that use Javascript within their web
page, they can query the device to have it report what is its
local IP address. When I look at Settings -> General -> About
Phone -> Network settings, 4 IP addresses are listed for my phone
(but not which one is for which type of connection from my phone -
wifi, cellular data, Bluetooth, something else). Only 1 is
reported by the what's my IP sites that I tested.
There have been times when an ISP or e-mail provider has
blacklisted a huge e-mail service, like Microsoft blacklisting
Yahoo, so Yahoo senders cannot reach Microsoft recipients. You
would think e-mail providers would not blacklist (have a whitelist
that overrides their anti-spam blacklisting) the other major or
well-known good e-mail sources but it has happened. You could try
to chat with Comcast to report they are blacklisting your cellular
provider's data service. You could chat with your cellular
provider to report they are getting blacklisted by Comcast. With
only a cellular data connection, I doubt Comcast has your phone's
local IP address blacklisted. More likely Comcast blacklisted
your cellular provider's data host (as that would be the source of
the connection to Comcast).

I haven't had much time to deal with this lately, but I have started
keeping a log of my mobile connection IPv4 addresses. I've been
surprised to find that I seem to always get one of about 5 addresses,
even when I connect 20 or 30 miles from home. That's not what I
expected to find, but it makes the blockage more understandable. It
appears that Comcast is blocking some of AT&T's addresses. Not a whole
block, but select addresses within a range. One of these days soon I
guess I'll have to call Comcast to complain, but I predict they won't
have a clue about what I'm talking about or be willing to do anything
about it.

To make it more complicated, sometime I DO get an address that's
permitted. Like this morning I was able to connect and retrieve mail,
but I tried again just now and I got an address just a couple of slots
away from the previous one, and I was denied.