Outlook 2013 sending emails too slow

Question

We have Outlook 2013 and the problem is that with some of the users, the emails just won't leave outbox quickly and will stay there for a long time. Uploading attachments is excruciatingly slow. Although, if webmail is used, the files are uploaded very quickly. What could cause this issue?

Answer 1

Short answer: the possible causes of this problem are so widely varied that it may be that nobody at superuser can offer an easy answer; a lot of troubleshooting by a tech expert may be necessary to find and fix the cause of the problem.

That said, here are some troubleshooting questions:

1) Is any other internet traffic slow for them? In other words, would it for example take them a lot longer to copy a large file to a network share drive than it would for other users, or does it take them longer to download a large file than it takes for other users? If so, it may be a problem more general than just Outlook: all internet traffic to and from their computers may be slower, and the expertise of a network admin or savvy person is needed to troubleshoot (as described above) to get their internet traffic faster. All kinds of things can cause internet slowdown, including inferior routers, or:

2) Do their computers generally run more slowly than other users' computers? For example, does a resource-intensive application take longer to start up on their computers than it does for other users? If so, there may be any of a wide variety of problems that cause their computers to run more slowly, including too much memory and hard drive space being used (or there not being enough of either), or having too many resource-intensive applications or browser tabs open, or Windows impolitely downloading huge updates in the background without notifying them, other software auto-updating, the Windows Search service doing user-unfriendly intensive indexing without telling them, malware hijacking their network traffic and abusing their workstations as part of a botnet, a hard disk defrag running, a virus scan running, some other users who share their network router may be hogging network bandwidth by streaming video or music or torrents, or any combination of all of these, yada yada yada yada YADA . . . :)