Don't use trend Micro sounds like a safe way. But seriously you been to ask them how to drive their anti virus program. All I can really tell you is use something else.

Have you tried going into the program's settings and turning off the anti-spam feature to see whether that makes any difference?

Also, it's generally not a good idea to allow real-time scanning of folders containing mailboxes, so if you can make an exception for your profile folder, that's worth a try.

jscher2000 -- Thank you for responding. I've been away. Today Trend Micro uninstalled the 2015 program and installed the newest 2016 version plus some new hot fix. This is what's going on now:

TM is running slightly better with Thunderbird, although still slow to respond much of the time. Here are some problems I've had since they installed the 2016 version earlier today.

(1) Typing in a reply was frozen mid-sentence for 30 seconds; then the missing words appeared and I was able to continue. (2) When opening a new message, the screen grayed out again and froze with the message "not responding" at the top for 10 seconds -- but then came back. (3) When I tried to delete an "unopened" message in the incoming screen, the screen grayed out and took several seconds to return -- but the msg was deleted. (4) Very slow to open folders in the left sidebar.

I have previously used Avast (the free version) and F-Secure (more expensive) antivirus programs with Thunderbird and had no problems at all.

I asked TM about your suggestions. They felt turning off the anti-spam would leave me too vulnerable. The Mozilla program file is listed in the Exceptions box. And I don't know where or how to access the "profile folder."

Can you give me any more help? Jonelle

Hi Jonelle, I probably can't help much, since I changed my system many months ago and no longer use Thunderbird on a daily basis.

I don't think an interruption of typing is related to anti-spam, unless a whole lot of emails were received while you were typing. But I guess the question is whether you mind testing with that off for an hour or two, long enough to know whether it makes any difference.

Oh sorry, there is an article about the location of the profile folder: Profiles - Where Thunderbird stores your messages and other user data

This is under a hidden folder, so if you haven't already, you may need to turn off the Windows feature of hiding "hidden" files and folders. This article has the steps: http://windows.microsoft.com/en-us/windows/show-hidden-files

Thanks for your help! I've found the folder and have added it to the Exceptions. I'll see tomorrow whether it helps.

Recent experiences with other anti virus programs indicates you should have an exception for the file NSmail.html in your temp folder. (Helps sometimes with writing mails) as for turning off the anti spam causing you issues. I would be very interested in exactly what is exposes you to, other that a few more mails for Thunderbird spam filtering to manage for you.

The first lesson I learned when dealing with anti virus vendors is do not accept anything they say at face value. They tell you you will be exposed, you press for details and they will tell you it is another line of defense. You ask a line of defense against what> and they usually offer a generic malware.You will go full circle. Why? Because most of what anti virus programs do is unnecessary and actually unhelpful. YOU DO NOT GET A VIRUS OR OTHER INFECTION FROM SPAM. Fundamentally spammers are selling stuff, they are not interested in your credit card details any more than anyone else selling products is. Malware comes on legitimate looking mail, Not spam.

Now an Anti phishing tool has a use in security, an Anti spam tool does not.

I'm not that concerned about spam; Thunderbird nearly always puts it in my Junk folder. Trend Micro is not very knowledgeable about Thunderbird ("not one of our clients"), so I am still muddling through, with slow-to-open new emails, long waits to open an email after sending a brief msg, the screen graying out if I try to open two in quick succession.

I've added a profile file and a profile folder to the TM Exceptions. My temp folder is empty; I cannot find an NSmail.html file.

TM's latest suggestion is to (1) check to see if TM is updating while I'm trying to open msgs, (2) exit TM when opening Thunderbird, let the emails "settle," then turn it back on, and (3) said attachments are not scanned until I open them, and (4) they don't know how to turn off the scanning of my emails for the above reasons.

Any suggestions for any other program when I don't renew TM?

the nsmail file appears for only a few seconds as mail is composed to send. I recommend the exception, even though the recent issues have been with it have been avast as a precaution.

As far as the trend exception for your profile is concerned. Looking through their documentation http://esupport.trendmicro.com/en-us/home/pages/technical-support/1059964.aspx

I think that the exception is for just the folder, not it's sub folders, so you best go to the help menu and select troubleshooting information. click on the show profile button.

Now add the folder that appears to Trend (that is most likely what you already added), then the mail folder, imapmail folder and any folders they contain.

In addition to the "default" folder, I added an additional file specifically to the Exceptions: ImapMail\imap.googlemail.com and my new emails opened quickly; I am able to move around much faster now. We'll see. . . Thank you.

Perhaps this is worth a read https://support.mozilla.org/en-US/questions/1078883. I am interesting this as a cross link as the other person is not having much luck with Trend.