is the text in the body of the email? Have you looked at Ctrl+U to see if it appears there. If it is in anyway important, the sender may have included it as an image.

After I opened the e-mail, typed CTRL+U and look using CTRL+F I founded the number I am using in filter in the message. So, it is not an image.

I am just wondering. If your account is IMAP, then have you set the filter to run after classification?

Most filter actions only apply to the header of the email and filter execute as early in the download as possible. Knowing when the body is actually available post download to filter against can be a problem and something which appear to affect IMAP accounts more than POP ones. Moving the filter execution to after classification means that the body must be there as it is used in junk filtering and generally it fixes issues where the body is not initially there when the filter would normally execute.

Personally I just run filters after classification as it make them just a little more reliable.

I think that isn't the case, because I am running the filter manually. Tryied even with other words in the same e-mail and doesn't work either. But I changed to after classification and doesn't worked also.