I know DialUp is not well used anymore, but I have a few dialup customers still, and I have even tested this myself, but with SmarterMail v13.1 I am getting customers complaining about timeouts when downloading attachments.
The customers are saying they are receiving "Your connection has been reset" using Internet Explorer.
Again I have tested this in-house, with IE, Chrome and FireFox, All have issues with file attachments, even using File Storage, and the url to download, it reset or timeouts.
It does this after a few minutes on files sizes of 1MB or so. I will do more testing to get exact times, and sizes. It seems liked SmarterMail v13.0 was okay, but somewhere around v13.1 is started happening.
I know it is holiday time for SmarterTools, so their support will be slower, so I am posting here first.