Put a brief explanation of the nature of the E-mail (like "question about paper") in the subject line.

请在标题栏中给邮件性质写一个简短的说明（就像“关于论文的问题”）。

youdao

Nothing says I'm too lazy to get offline like an E-mail with the subject line "will you marry me." And please don't think adding in a clever kissy smiley face will help matters at all.

懒到发一份主题为“你愿意嫁给我吗”的求婚邮件就匆匆下线，你别以为加个可爱的亲吻笑脸就能一切搞定了。

youdao

And rarely, if ever, can I get past the subject line in my e-mail inbox.

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