Mine has been a bit sluggish this last week also.
Here's a couple of speed testers-
http://myspeed.visualware.com/
http://www.speedtest.net/
http://www.speakeasy.net/speedtest/
on the first link this was my results-
Download speed 475 Kbps
Upload speed 100 Kbps
D/load QOS 66 %
U/load QOS 87 %
RTT 162 ms
Max Delay 196 ms
Avg Delay 24 ms
Max Bandwidth 736 Kbps
Route Speed 3236 Kbps
Forced Idle 0 %
Route Conc 1.5
some of it could be kids out of school, unemployed workers - the more people using slows everything down.
but that shouldn't affect getting email unless it's timing out before connecting to email server?
Could the email have gone to a spam or junk folder?
sometimes I do a test by sending an email to myself from one address to another one- to see how long it takes..
If it is the actual dsl that is slow then not much you can do for that, but if the computer has some slowness you can do tune up stuff for that.
I would be interested in what your test numbers come up as - to compare with mine..