Thunderbird 38

Anyone else finding in TB 38 that the first SMTP send per session doesn't work, and then the second and subsequent sends work fine? This started happening to my mother when she accepted the upgrade to 38.1, I think it was (or maybe 38.0.1?) and I'm seeing the same behavior now that I've applied the update to 38.2.0 (from 31.7.0 I think). The UI gives a "timeout" error popup, but IIRC looking in the log on her computer revealed that on the first attempt it was actually not even trying, just instantly failing, I think without even opening a connection, so I suppose the same thing is happening here since I'm seeing the same symptom. (The second transaction looked like a normal SMTP send, hence successful send of mail.) enotsola and I both banged our heads against this issue for several hours when she first saw it happening and got nowhere; apparently no one else on the internet was having this problem then, and I'm not finding references to it now, either. bzuh?