I would suggest confirming the fact that the comcast account can't send, because if it can then it is pointing back to OE as the problem.
Have you checked the Hotmail account settings that a) you have Remember Password checked and that the Outgoing email server section has the My server requires authentication and that the Settings (button) window reflects that user name and password (or has been set to Use same settings as my incoming mail server).
I qualified the statement about hotmail, if it was a web mail account, OE can still download it using webdev/deltasync and for that reason isn't using the POP3 protocol so couldn't be scanned. However, if you are using a hotmail POP3 account as I asked and you confirmed, then it uses the standard email POP3 protocol and can be scanned.
All the hotmail settings are fine. I checked all of that originally when I first had this problem a week or 2 ago. I never touch the settings, but removed the password that was prepopulated and re-entered it in case that would fix it, but it didn't.
I haven't had any problems sending from Comcast at times that OE won't send hotmail, but I wasn't sending to Aol. I am not going to use Comcast to send anything I don't already, because I try to keep that one spam free as much as possible, and the more people who have it in their address book, the bigger the chance of it getting passed to strangers. What I did the first time I noticed this problem, was send myself a message from comcast to comcast to make sure it would go thru, and it did.
If I knew for sure that updating Avast would eliminate this issue, I would do that now, but I am afraid I am just going to end up with further problems that are worse than this, because I've seen a lot of posts about problems happening when they updated. I like to wait as long as possible before updating things, since the time I had a major problem happen when I did a Windows update as soon as it came out. That's also why, besides virus databases updating automatically, I don't have any programs set to auto update, so I am in control of when the update happens, and will know what to blame if a problem happens. That's why this one is so frustrating to me, because I didn't change anything, and still developed a problem, and the problem doesn't even happen consistently, just intermitently. I was just hoping that posting it would show me that I am not the only one, but even though someone did post a similar problem today, you invalidated it just because it's a different version of Avast. Are the versions so completely different that they couldn't have ONE thing the same that is causing this?