I would like to know if this is possible as well. Outside of naming the file initially when attaching it to the data provider, I do not know if there is a way to define the file name or do it dynamically. I see the option to use Date or Revision in the Export File Name on the File Maintenance > Synchronization tab but do not know if that works or not. 

The Date and Revision options in the Export File Name do work. If you choose Date, the file name is "STOCKEXPORT_2022_08_11_14_31_46.csv". If you choose Revision, the file name is something like “STOCKEXPORT_5.csv”. 

As it doesn’t seem there is a way to keep the file name fixed in Acumatica, the web developer will need do something on the import end, e.g. striping off the revision from the file name. 

@yisong, I found that if you name the file in your path of the synchronization that it will set the file name accordingly. This is now working at a site where a third party product is picking up this particular file name. 

I cannot seem to get this to work. I get a permissions error, although the file permissions at the SFTP site has full rights. Has anyone found a way around this? Customer does not want the date or revision extensions.

I was able to get the the suggestion from stephenhennelly to work. The problem was sending a file to an SFTP site verses an FTP site. The FTP site allowed an overwrite of the file with the same name.