Outlook Error 0x80042109 usually appears when a user tries to send an email. In such scenarios, the email does not move outside and Microsoft Outlook starts showing an error pop up on screen with the given below message:
Error Message: Task 'SMTP server name - Sending and Receiving' reported error (0x80042109): 'Outlook is unable to connect to your outgoing (SMTP) e-mail server. If you continue to receive this message, contact the server administrator or Internet service provider (ISP).
Error code and message 0x80042109 in MS Outlook directly defines that email client (Outlook) is not able to establish a connection with Outgoing email Server. Generally, SMTP protocols are the factors behind Outgoing emails, if the details of these protocols are assigned wrongly, then it can cause such kind of errors in Microsoft Outlook.
Other common, but the major cause of sending and receiving errors in MS Outlook error are scanning programs. So, if there is any scanning program like Antivirus & Firewall is currently running, then make sure about their settings or disable it.
Outgoing Server Detail (SMTP) in Outlook includes some advance values like Port Protcols and SSL authentication over protocols. These Outgoing details make possible of transformation (Sending & Receiving) of emails via Microsoft Outlook. Wrong inputs of these values or alteration from the ISP side can raise up errors like 0x80042109 in Outlook.
The default SMTP details for Outlook is "25", but after alteration in this value you need to reset it by "587". As an alternative, a user can also contact with their ISP (Internet Service Provider) to troubleshoot this issue.
Note: Please follow the given path to reach out at the Account Settings Windows in Outlook 2010 & 2013:
File >> Options >> Account Settings >> Account Settings
Note: Sometime manual method fails to overcome corruption issues cause due to inappropriate reasons. At that instant there is no other solution then switching to a third party utility like PST Recovery, as it is capable in fixing error issues and retrieving corrupted data file into a healthy one.