If you check you Inbox at your email providers webmail page are there 2 copies of the message shown there?

It appears that the problem is with our service provider -- Xfinity. Will try to get it resolved with that company. Thanks.

That or it the person sending if it is just from one person.

I deleted the duplicates. I'll double check.

My provider is AT&T, this started a couple of days ago - for all 3 gmail accounts & 1 for Bell South (have had this mail probably 5 yrs) up to then, all my mail went thru Mindspring... My phone actually gives me a count on messages rec'd and it also shows 2 when in fact, there is only one...AND this has been going on for eons!!!

I have this problem and I have checked my email provider (Microsoft Outlook) and only 1 copy of each email is displayed. Duplicating every email when I have 4 email accounts is just creating unwanted overload. I know that in the IT world it is easier to blame other software/service providers for almost every problem but that just adds to the work load for the end user. If Thunderbird do not know the solution please just say so and save us a lot of time. In this case there has been plenty of time for Thunderbird to figure out a solution so if you don't know now the likelihood is that we will not be given a solution. Regards Trevor Perth Australia