Server

• Check the email server. Occasionally an email server has issues that cause the email message to "time out" when trying to attach a file. The server may just sit and act as though the process is still being completed, or you may get an error message. You can report such errors to server administrators, but because the problem is with the server and not on your end, there is little else to do except try a different provider.
  
  

File Size

• Look at your file size. Most email providers have limits on the size of the files that can be attached, so if your file is too large, you may not be able to attach it. You can try zipping the file (making it smaller through file compression), or you can split the file into parts and send each part separately. Zipping the file usually works best, because splitting the file can be a hassle and time consuming, depending on the file type and information included within it.
  
  

File Type

• Confirm any file type restrictions that the email server may be employing. Some file extensions are not allowed by some email servers and thus cannot be attached to an email message easily. For instance, some email servers limit the attachment of files with the extension .exe. This is because this file extension is associated with a program, and to prevent the spread of computer viruses, some servers don't allow program files to be attached. You can get around this in most cases by changing the name of the file, but you'll have to tell your email message recipient what you've done so they can run the file once it is downloaded.
  
  

Virus Scanning Programming

• See if the server's virus scanning programming is causing an issue. Most email servers use virus scanning software so that viruses and trojans aren't spread through the email attachments, but occasionally the software identifies a file as a virus or trojan threat when there really is nothing wrong with the file. The file thus cannot be attached because the virus scanning interferes with the attachment process. The best option is to try to re-create the file and attach the re-created version.