接続が切れているのであれば, エラーを返すべきでしょうね.
これでどうですか? flim/smtp.el に当てて下さい.

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dt/15mX/GrI7M0/RGzobewSflmCchaqUpShFxbTpOsAR8ALob9XlhYh4229q+DL2
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nFIr6ZVhcDYQKmejsSOx1+HNjy46VKfWX2PQU6txcMbG7SKZLXLrIuSBWq9O2Dl/
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/ZsONCmnybNsZWVlZeXf4Ae2+ZtMAAoAAA==
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