You drop Thunderbird by uninstalling it from your computer. All done. Now I had to make some wild guesses as to what DRN was. I was pretty sure it was not the Disaster Response Network, the Digital Road Network or the Digital Regulation Network but as an Australian I am sure Google is biased to offering me what they consider local solutions. I did, thanks to Google, locate a US based cooperative offering Internet services in North Dakota and I feel that is probably the provider you are referring to. One of the things I did observe is that their web site makes little mention of emails at all. However they do provide settings here https://www.drn.coop/internet-support/email/ which is offered as For IMAP: Incoming Server: mail.drtel.net – Port 993– Authentication: Normal Password – Security: Depends on the Client Outgoing Server: mail.drtel.net – Port 587 – Authentication: Normal Password – Security: Depends on the Client Researching this domain I learned that this DRN is actually Dickey Rural Telephone Cooperative. https://dawhois.com/ Have you contacted then about your issues? # You say you had some updates from Gmail and ignored them. What makes you think they are relevant? # Does your email address end in @Gmail.com? # What exactly is the error message you are receiving? # Do you have an antivirus program installed?;What is it? I think you need to be aware this is a public peer support forum. No one get paid and normal consumer threats mean nothing. You will note I started by answering your first question, how to drop Thunderbird. Really if you choose not to use Thunderbird does not bother me. I am prepared to give my time to try and assist you but I do not respond to threats of "I will take my business else where" well at all. Your statement " I am ready to uninstall Thunderbird and go with gmail only" only leavers me wondering what Gmail actually has to do with this at all. So please elucidate, I think it will be quite informative.