Hello chairsofa,

Would you please take a look at this :

https://askleo.com/can_i_stop_or_unsend_an_email_i_sent_by_mistake/

And also :

http://kb.mozillazine.org/Recall_a_message

In case it applies to you, note that scanning of outgoing mail by security/AV programs is a common cause of slow sending. Disable that option if it's in place and see if it makes any difference.

Thank you for your replies. I spend most of my time on a boat. The internet can be really slow out here in the Caribbean. I'm well aware that once gone, the message cannot be recalled. What I want to know is if the message is going out very slowly, purely due to slow internet, can I stop it, and then send it later when the internet is better? This is especially the case if I have some attachments, and all it takes is a is a megabyte for the message to take sometimes 10 or 20 minutes to send.

Hello again chairsofa,

The reason why you want to '"unsend" or recall an email doesn't really matter, I'm afraid. Maybe just put off sending emails till it's a better time to do so (?)

Sorry, not solved yet. If I know when my connection would slow down, then sure, I wouldn't send it. But sometimes starts fast and then crawls. Oh well, life on a boat is great otherwise. An old version of Apple Mail has a cancel button (actually a small circle with an X) that stopped any messages in the process of being sent, or queued to be sent. Apple, of course, deleted that (they love deleting features). Hopefully trying to find something equivalent in Thunderbird. Thanks again for everyone's help, and maybe further ideas?

Unless sfhowes' suggestion applies to you, there is nothing you can do once the message has been sent .....

I understand fully there is nothing to be done once sent. I am asking about cancelling in middle of sending, and not sending any queued messages to be sent immediately after the slow message.

May I ask if sfhowes' suggestion applies to you  ? (you never said ...)

All I can think of now, is to give you these to look at :

https://superuser.com/questions/105988/thunderbird-undo-send-feature-like-in-gmail

https://www.getmailbird.com/the-best-way-to-unsend-email/

This isn't a means for cancelling sending, but it might help with a slow connection: Preferences/Advanced/General/Config. editor and raise the preference mailnews.tcptimeout from its default value of 100 sec.

http://kb.mozillazine.org/Can_not_send_large_attachments

McCoy: Thanks for your response; the first link was especially useful. Sorry I forgot to mention that sfhowes' suggestion from a few days ago does not apply to me as I am not scanning my outgoing mail. sfhowes: I will try adjusting the mailnews.tcptimeout

Thanks to everyone for your help

I tried to put solved beside both sfhowes and mcCoy, but it would not accept a second 'solved'. Thanks to you both, and to everyone who had suggestions.

chairsofa said

sfhowes: I will try adjusting the mailnews.tcptimeout

Hello again chairsofa,

Should you find that sfhowes' suggestion actually does solve your problem : please, remove the Chosen Solution mark from my post and mark sfhowes' post instead.

You can do so by clicking on the "Undo" button to the right of the post that you now marked as Chosen Solution.

In case non of our suggestions really solved your problem, but you just want to close this thread : you could just mark your own (last) post as Chosen Solution ......

(who said computers would make your life easier, eh  ?)