Main.dll is being used by another process

I’ve been automating collecting demographics changes data from our software and automatically emailing it to another team. I’ve been using “Send SMTP Mail Message” to do this but I can never run this process a second time without having to restart my system as it throws this error:
The process cannot access the file ‘\\home\users\rva10\documents\UiPath\VSDemoExport.local\install\VSDemoExport_Expressions_Main.dll’ because it is being used by another process.

Another thread I found on this topic suggested it was the mail process that is using it but I have found no solutions to this issue.