sendmail, 4th Edition

The Temporary qf Rewrite Image: tf

When processing a queued message, it is often necessary for sendmail to modify the contents of the qf file. This usually occurs if delivery has failed or if delivery for only a part of the recipient list succeeded. In either event, at least the message priority needs to be incremented.

To prevent damage to the original qf file, sendmail makes changes to a temporary copy of that file. The temporary copy has the same queue identifier as the original, but its name begins with a t.

After the tf file has been successfully written and closed, sendmail calls rename(2) to replace the original with the copy. If the renaming fails, sendmail syslog(3)s at LOG_CRIT a message such as the following:

cannot rename(tfdB91brx04175, qfdB91brx04175), df=dfdB91brx04175

Failure to rename is an unusual but serious problem: a queued message has been processed, but its qf file contains old and incorrect information. This failure might, for example, indicate a hardware error, a corrupted queue directory, or that the system administrator accidentally removed the queue directory.