Hello,@Darshit Chokshi
Good day! Thank you for bringing this issue to our attention.
I understand how frustrating it can be to encounter error code 0x80040610 when trying to send emails in Outlook, especially when the message indicates that the size exceeds the established limit, even for short emails.
You're receiving error code 0x80040610 in Outlook, which prevents you from sending any emails, with the error message indicating that the message exceeds the size limit established for your user account.
You have noted that this issue occurs regardless of the email's length, which suggests it might not be related to the actual size of your emails but possibly to an issue with your account settings or Outlook's configuration.
Here are some steps you can take to address this issue:
Use the Outlook Inbox Tool:
As the error code 0x80040610 is a send/receive error, corrupt Outlook data files may cause it. To fix this, run the Inbox Repair tool, as it can scan the data files.
Navigate to the folder according to your Outlook version.
2021/19: C:\Program Files (x86)\Microsoft Office\root\Office19
2016: C:\Program Files (x86)\Microsoft Office\root\Office16
2013: C:\Program Files (x86)\Microsoft Office\Office15
2010: C:\Program Files (x86)\Microsoft Office\Office14
2007: C:\Program Files (x86)\Microsoft Office\Office12
Launch the EXE file, select Browse for the .pst file you want to scan, and click on Start.
If any errors appear in the scan, click on Repair to fix them.

Modify Outlook Account Settings
Open Outlook and navigate to File > Account Settings.
Click on the Email tab and double-click on your email account to modify/view its settings.
Check if you have set the correct Incoming and Outgoing Server names in the corresponding boxes.
Now click More Settings and place a checkmark at the corresponding box in the Outgoing Server tab.
Navigate to the Outgoing Server tab and check the My outgoing server (SMTP) requires authentication option.
Click on OK once done, restart Outlook, and check if the error’s fixed.

Increase Attachment Size Limit
Press Windows + R to open Run, type regedit, and hit Enter.
Once the Registry Editor opens, navigate to the following path. Manually create one if it does not exist.HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences
Create a new DWORD (32-bit) Value in the right pane and name it MaximumAttachmentSize.
Double-click on the newly created value and set the value data to the allowable attachment size. For example, set 0 for no limit and 30720 for a 30-MB limit.
Click on OK once done to save the changes.

Run Outlook in Safe Mode and Disable Add-ins
Press and hold CTRL, then double-click on the Outlook.exe app icon.
A prompt will now ask, “Do you want to start Outlook in Safe mode?”; click Yes.
Select your Outlook Profile Name in the next screen and click OK.
Outlook will now open in Safe Mode. If the error 0x80040610, The message being sent exceeds the message size, doesn’t occur in safe mode, one of the Add-ins may be causing the error. In that case, disable Outlook add-ins.
Disable the Windows Firewall and Antivirus Program
Open Control Panel > Network Connections > Right-click on Network Connection > Select Properties.
In the Properties, under the Security tab, you will find the Firewall option. Turn off the option and see if the problem is fixed.
After your inbox is updated, you can again enable the firewall.

Repair Outlook:

If none of these suggestions could help, repair the Outlook app. Here’s how:
Press Windows Key + I to open Settings and navigate to Apps > Apps & Features.
Click on the office product you want to repair here and select Modify.
Click Online Repair and follow the instructions on-screen.
Note: Remember to always back up your Outlook data before making any significant changes.
I hope these steps help resolve your issue. If the problem persists, please let us know, and we will be happy to assist you further.
It was pleasure working with you on this issue. We appreciate your patience with us.