I think using some better practices will help here. It will certainly narrow down the number of possibilities of things that could be going wrong.

First: As a Windows computer technician, I cannot stress enough that Windows has to be rebooted occasionally. There are always people that will say that it is not necessary, but they are ignoring reality. Windows gets screwed up over time and rebooting fixes many things. I generally recommend shutting down the computer at night. Failing that, then manually reboot the computer. How often you need to reboot will depend on how much you use your computer and how many different programs/apps you use. If you use it more than about 3 hours per day, I say reboot every day. If you are using your computer less than 3 hours per day, then there is no need to keep it running all the time. Shut it down.

Reboot your computer, then please read and follow the advice in this article for best practices when using Thunderbird: Keep it working - Thunderbird

Following my advice and all the advice in that article may fix your problems. If not, then at least many things have been ruled out as your problem(s).

Thank you for responding, but your suggestions are not a fix for my problem. Actually,I am not inclined to give much weight to your comment because you give no basis behind the assessment that all Windows operating systems need a reboot every day. I worked in technical fields and have worked with computers running under MS DOS to Windows 10. I know daily rebooting was required with much older operating systems like Windows XP, but I can think of no reason why that process for those old operating systems is required for the considerably more advanced OS like Windows 8.1. Can provide me with detailed explanation behind that assessment?

As to rebooting, my Windows 8.1 operating system and other software/apps are automatically updated, most times requiring a rebooted to complete the installation. This happens at least once a week, if not more frequently. The sending or receiving problem is not better or worse after those reboots.

Thanks for the pointer to the best practices suggestions, but I am already doing every thing suggested in the Routine Usage section. I set Thunderbird to automatically do database compression. The In Box is normally empty except when messages do not meet filtering guidelines for placement in topic related sub folders. All folders, including the Junk and Trash folders are routinely purged of old or irrelevant content then compressed. I do not store message on the server of my network provider. All messages should be loaded into my computer as they arrive, when I open Thunderbird, or when I click on Get Messages.

I don't have the energy for it, and it is outside of the scope of this forum for me to explain why I know that Windows needs to be rebooted regularly.

You profess experience and knowledge about Windows, and your opinion about rebooting Windows is firm, so I'm sure that anything I could say on the subject would be discarded by you. I hope that your computers work well, but I'm sure that if you have a modicum of intelligence, one of the first things you do when something doesn't work properly, or doesn't make sense on one of your Windows computers, is to reboot it.

Hopefully someone else will try to help you here with your Thunderbird issues.

I guess if maybe you were willing to put as much effort into supplying information I requested in clarification as versus writing in an attempt to dis and insult me ( see "You profess experience", "your opinion" "if you have a modicum of intelligence") this would have gone far better and I would be closer to understand your suggestion. I don't know why, given the tone of your comments in response, you are allowed to provide advice on this blog.

1. This is not a blog. It is a support forum.

2. Everyone who responds here to help people are volunteers. No one is being paid to help you. If you don't like this, then buy an e-mail program where you will get paid support.

3. You saying that you are not inclined to give much weight to what I have to say, doesn't endear you to me.

4. I have found that people who profess knowledge and experience, and discount what I have to say, usually will not follow instructions in solving problems, because they think they know better than I.

For all those things, I have absolutely no desire to explain myself to you, or waste time helping you.

"I have absolutely no desire to explain myself to you" Which you in just did to maintain your over inflated assessment of yourself.

Which I did because you wanted an explanation, you ijit. You dissed me first.

Now that you have marked your question as "Solved", no one else here will read the thread. I guess you don't want help after all.

Goodbye and good riddance.

Oh, Gosh! I am so hurt. Calling me a name. You must feel so so much better getting that of your chest.

Your level of social incompetence makes you incapable of offering assistance in any mode less than lording your over inflated ego a as substitute for real knowledge.

I pity the people that have to suffer your acquaintance in person.

Why don't you try reading the support I've been giving to other people here? Maybe you might learn something, like I am able to help people fairly well, as long as they don't come off as know-it-alls who insult me.

If after reading the help I give others, you believe that you can do better, I dare you to try. You won't, though, because you wouldn't get paid. You would have to do it out of the goodness of your heart. I don't think that would be possible for you.

My guess is that you would rather continue to insult me than do anything worthwhile.

How little you know about how absolutely wrong you are. I volunteer at a soup kitchen, a food bank, as a handyman for a non-profit organization helping to keep elderly and disabled people in their homes, as block organizer for our Neighborhood Watch, assisting neighbors with yard and house projects, and giving extra produce from our garden to senior centers for distribution. All for no charge. In fact I eat the cost for some because they can't afford it and donate 10% of my gross income to other non-profit organizations.

All the people I give my time and effort to appreciate my intelligence, experience, humor, and attitude toward helping. There are articles in the organization newsletters as an example of a prime volunteer and those serve regularly ask for me specifically.

Anything you might have to say about my life or personality means absolutely nothing, you e-jit.

Now who's stroking their ego?

If these people you help questioned your skills and intelligence, insulted, belittled, and baited you, you probably wouldn't have much patience with them either.

I like to help people too. I wouldn't be in this support forum if I didn't. I do help people here, despite what you think. That is not bragging, just a statement of fact. I do it because I want to help, and to feel useful.

Another fact is that I don't have patience with people who ask for help, then say they are not inclined to take what I say to help them seriously. It becomes clear that they don't seriously want help, they just want to complain.

I should have left it at that because I don't like conflict, but you have a talent of insult, sarcasm, belittling, baiting, and generally tearing people down that is bullying behavior. I responded, because I will not be bullied. Unlike you, though, I have never wanted to cultivate such bullying talents and skills like that, so my efforts to respond fall short.

If only you used a fraction of the time you have just spent attempting to belittle me in answering this question. It seems to so easy to get you, with an over inflated ego, to blather on and on attempting to defend that ego. I have never done this before, but it seems easy to waste your time given need to feel superior. You always have to have the last word. You made it into a game now to see just how much of your valuable time I can waste in these exchanges Mr "I don't have the energy for it".

Jherndon said

If only you used a fraction of the time you have just spent attempting to belittle me in answering this question.

You made it clear that my opinion + advice help was useless. How could anything more I said on the subject of you question be heeded? Why would I try?

It seems to so easy to get you, with an over inflated ego, to blather on and on attempting to defend that ego.

I have not been trying to defend my ego and I don't need to feel superior. It is a matter of principle to stand up to a bully.

You made it into a game now to see just how much of your valuable time I can waste in these exchanges

You are the one who has made this a game. Baiting me, and apparently having fun doing so. You seem intent on knocking me down, to try to make me miserable, and you enjoy it. A person who enjoys such a thing is not a good person.

Yep, Like I said. Last word.

Ha!

You are ascribing your own motivations on to me. Thanks for the laugh!

You make this so easy. Perhaps there will be a condition named after your inflated ego.