Email Sync error on new Comcast email account

Question

Email Sync error on new Comcast email account

Steven LaMotte 25

Comcast migrated over to yahoo. Spent 1 hour on phone with yahoo tech to set up correct server settings using yahoo app password. When I log into Outlook app on my desktop I can see my Comcast email account, but I can't send or receive emails and get a sync error. Yahoo tech said everything is set up correctly and that sync errors are part of outlook.

Can you please help me?

Thanks, Steven

Moved to Microsoft 365 and Office | Other

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Answer accepted by question author

Hornblower409 14,970

New Outlook for Windows - Adding a Comcast Xfinity account that has been migrated to Yahoo

For Classic Outlook for Windows instructions, see the Answer by "Hornblower409 Apr 16, 2026" in
https://learn.microsoft.com/en-us/answers/questions/5663018/outlook-wont-let-me-sign-into-my-imap-server

1 -- Remove your Comcast account from Outlook and restart, or Add a new account.

To remove an existing Comcast Account do File -> Account info -> Select your Comcast account, [Manage] and [Remove].

If you have other accounts already setup in Outlook do File -> Account info and [Add account].

Once you get to the Add an Account screen. Enter you Comcast email and [Continue].

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2 -- Outlook will spin it's wheels for a bit

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3 -- Then give up and ask you what to do next. Click [Select Provider]

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4 -- Pick Yahoo

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5 -- Outlook tells you what it wants to do. [Continue]

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6 -- You should see a browser window open that ask you to logon to Yahoo. Give it your Comcast email and [Next]. Provide your Comcast account password and whatever else is required to logon to your Comcast/Yahoo account.

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7 -- In the same browser window you must agree to let Microsoft access your Yahoo/Comcast data.

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8 -- The action should move back to Outlook which will finish adding your account.

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9 -- And you made it!

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If this doesn't work for you, tell me what step number went sideways.

Steven LaMotte 25 Reputation points

2026-04-26T00:29:20.37+00:00

This work great. Thank you!

3 additional answers

Your answer

Steven LaMotte 25 Reputation points

2026-04-26T00:29:20.37+00:00

This work great. Thank you!

Answer 1

Steven LaMotte 25

I've done all of your suggestions. I've spent time with both Comcast and Yahoo support, and they have verified that all the settings are correct. It is a Microsoft Outlook sync issue. Please help.

0 comments

Answer 2

Blood Vine 30

Hi Steven,

Thanks for the detailed issue when you said that you've spent time with both Comcast and Yahoo Support and they are saying everything is synced that helps narrow things down.

If Comcast support and Yahoo Support have already confirmed the migration and app password/OAuth setup is correct, then this is likely an Outlook-side account token or profile sync issue rather than a server settings problem.

Here are the most reliable fixes to try next (in order)

1. Fully remove cached Outlook credentials

Even if the account was removed in Outlook, Windows can still hold old auth tokens

Close Outlook completely
Go to Control Panel → Credential Manager → Windows Credentials
Remove any entries related to:
- Yahoo
- Comcast
- Outlook / Microsoft Office / Office16
Restart your PC

2. Create a fresh Outlook profile

This resolves a large percentage of "sync error but settings are correct" cases.

Open Control Panel → Mail → Show Profiles
Click Add
Create a new profile and set it as default
Re-add the Comcast/Yahoo account

3. Check Modern Auth requirement

Comcast migrated accounts now rely on OAuth (Modern Authentication).

If Outlook is falling back to legacy IMAP auth, it may connect but fail to sync. Creating a new profile forces a clean OAuth handshake.

4. Try Outlook Web as a comparison test

Log into: https://Outlook.com

Then see if the account behaves correctly there. If web works but desktop doesn't → confirms local Outlook profile/token issue.

5. Last resort: New Outlook vs Classic Outlook mismatch

If you're using New Outlook for Windows, some migrated Yahoo/Comcast accounts still behave inconsistently depending on rollout region/build version. Testing in Classic Outlook (or vice versa) can isolate that.

Bottom Line:

Since both Comcast and Yahoo have validated the configuration, the most likely cause is a corrupt or stale authentication token stored in Outlook or Windows, not incorrect settings.

Hornblower409 14,970 Reputation points

2026-04-23T21:59:04.6533333+00:00

@Blood Vine said

Try Outlook Web as a comparison test

The OP is trying to get a Comcast/Yahoo email account working. You can't use a non-Microsoft Account in Outlook Web.
Blood Vine 30 Reputation points

2026-04-23T22:46:00.1933333+00:00

@Hornblower409 said:

The OP is trying to get a Comcast/Yahoo email account working. You can't use a non-Microsoft Account in Outlook Web.

Actually it does work just as you can sign up with Microsoft under a different email. I have already removed my cached Outlook credentials and made a new outlook profile and then my Comcast/Yahoo account started working for sending/receiving emails.
Hornblower409 14,970 Reputation points

2026-04-23T23:14:56.39+00:00
@Blood Vine

Actually it does work just as you can sign up with Microsoft under a different email.

Using a non-Microsoft account as a primary alias for a Microsoft account does not mean that you can send/receive from that non-Microsoft account in any version of Outlook. It's just an account ID. A third-party alias serves as your login identity for Microsoft, but it does not link the actual mailboxes.

You can not use a non-Microsoft account (e.g. Yahoo) in Outlook Web.

https://support.microsoft.com/en-us/office/connecting-additional-email-accounts-in-outlook-on-the-web-is-no-longer-supported-d7012ff0-924f-4f78-8aca-c3912d886c4d

What version of Outlook do you have?

I use a web browser (Chrome, Edge, Firefox, Safari, etc.) -> Outlook Web

I use a Mac -> Outlook for Mac

I use a phone or tablet -> Outlook for Android or Outlook for iOS (iPhone, iPad)

I use a Windows PC and my Outlook menu has ONLY the tabs: File | Home | View | Help -> New Outlook

Else -> Classic Outlook

Answer 3

Steven LaMotte 25

That did not work for me. I have Outlook 365 and not the classic Outlook. Still the same cannot connect error.

Hornblower409 14,970 Reputation points

2026-04-25T23:31:43.4133333+00:00

@Steven LaMotte said

That did not work for me

Are you referring to the Answer from Blood Vine, Hornblower409 or both?

I have Outlook 365 and not the classic Outlook

If you say "not the classic Outlook" then that means the New Outlook for Windows? This article might help you determine exactly which Outlook you are using:

https://support.microsoft.com/en-us/office/what-version-of-outlook-do-i-have-b3a9568c-edb5-42b9-9825-d48d82b2257c

It is critical that we know what OS (Windows, Mac) and what version of Outlook you are using. The possible solutions are very different depending on that info.