Outlook for Mac has been unable to sync with my Charter server to upload incoming e-mails.

For a POP account in Outlook for Mac, the supported next checks are:

1. Verify Outlook is online.
   • In Outlook, open the Outlook menu.
   • Make sure Work Offline is not checked.
2. Confirm the Mac still has network access.
   • Open a web browser and verify websites load.
   • Since webmail works, the general internet connection is available, but Outlook can still fail if the outgoing or incoming mail path is blocked.
3. Recheck the POP account credentials and server settings.
   • Go to Tools > Accounts.
   • Select the Charter/Spectrum POP account.
   • Verify the email address, user name, and password.
   • If Spectrum requires special settings, confirm SSL and port values with the provider before changing them again.
4. Turn on SMTP authentication if it is not already enabled.
   • In Tools > Accounts, select the account.
   • Under Outgoing server, select More Options.
   • Choose the required authentication type and enter the credentials.
   • This is relevant because Outlook for Mac notes that some POP and IMAP accounts cannot send unless SMTP authentication is enabled.
5. Check whether the network or ISP is blocking the SMTP connection.
   • Outlook for Mac documents that a firewall on the ISP or network can block connections to the outgoing mail server.
   • If that is happening, an alternative SMTP server from the ISP or network administrator is required.
   • In the account settings, the replacement is entered in the Outgoing server box.
6. If the issue started with a message that had several photo attachments, check Drafts for a message that is too large to send.
   • Outlook for Mac keeps oversized messages in Drafts, not Outbox.
   • Open Drafts and look for the failed forwarded message.
   • Remove some attachments and try sending again, or delete the draft.
   • If deleting it, also delete it from Trash to fully remove the stuck oversized message.
7. If the mail server is unavailable, Outlook cannot send or receive.
   • Since Spectrum webmail works, the mailbox itself is likely available, but Outlook for Mac guidance still recommends confirming server availability with the provider when the client cannot connect.

Because the account was already removed and re-added, the most relevant remaining self-service steps are:

• verify Work Offline is off,
• verify credentials and POP/SMTP settings,
• enable SMTP authentication,
• remove any oversized draft message,
• and check whether the ISP/network is blocking the configured SMTP server.

Error 3253 is listed by Microsoft as one of the send/receive errors covered by Outlook troubleshooting, but the Mac-specific guidance in the available documentation points to connection, authentication, server settings, server availability, or SMTP blocking as the main causes.

If the oversized message cleanup does not help, use Outlook for Mac’s guided support tool or Help > Contact Support.

References:

• I can't send or receive messages with Outlook for Mac
• I can't send or receive messages in Outlook for Mac
• My email message doesn't send
• I can't send or receive messages in Outlook