when i try to send an email from excel 2010 as an attachment, i get an error message about my "ost is in use and cannot be accessed. close any application that is using the file, and then try again. you might need to restart your computer"
If It is creating problem then you should go for some softwares which will provide you e-mail support. There are many softwares available which will help you out such as Ninjatueup software.
Microsoft Excel topics include formulas, formatting, VBA macros and user-defined functions, and everything else related to the spreadsheet user interface, including error messages.
Start outlook in safe mode (start, run, 'outlook.exe /safe')
Then disable add-ins until you find the culprit.
If virus scanning you can exclude the OST file...
Have a look here:
https://www.experts-exchange.com/questions/28448240/Error-Outlook-ost-is-in-use-and-Cannot-be-Accessed-when-try-to-Send-to-Mail-Recipient-in-Outlook-2013.html