经过进一步认真检查发现签名是伪造的。

On closer examination it was found that the signature was not genuine.

《牛津词典》

由于将检查签名(出于安全性考虑)，因此原发件人必须从发送邮件的邮件文件收回它。

Because signatures are checked (for security purposes), mail must be recalled from the mail file from which it was sent, by the original sender.

youdao

在分析证书的有效性时，同时还会检查可信签名。

When the certificates are analyzed for validity, trust signatures are checked as well.

youdao

I also issued them a passport, put their picture in it, had them sign their names, check to see how they know their addresses.

我还给他们每人发了一个护照，把他们的照片放在里面，并让他们签名，从而检查他们。

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