I like to keep all my sent messages from multiple email accounts in a single folder. For years keeping them on a gmail imap account has worked. But recently, this stopped working and need your help. E.g., for the email service provided by my ISP (Cox Communications), in Account Settings / Copies & Folders I have "Place a Copy in:" set to Other: "Sent Email 2021 on foobar@gmail.com" (where my Gmail username substitutes for "foobar"). Yet when I attempt to send a message using the ISP account (and the ISP's SMTP Server), I get two error messages: # "'''Save Message''' Your message was sent but a copy was not placed in your sent folder (Sent Email 2021) due to network or file access errors. You can retry or save the message locally to Local Folders/Sent Email 2021-foobar@gmail.com." # "'''Thunderbird''' Server imap.gmail.com has disconnected. The server may have gone down or there..." (here the message breaks off). The second message also occurs if I try just to copy a message from a local folder to the Gmail imap folders. I'm using TB 91.1.2 on MacOS 10.13.6 (High Sierra) running on a Mid 2010 27" iMac.