[exim] meaning of abort for LMTP

The manual says that for the lmtp transport (describing the timeout
paramater):

"The transport is aborted if the created process or Unix domain
socket does not respond to LMTP commands or message input within this
timeout"

What exactly does "abort" mean here? In particular, does it mean the
message will be retried later? Does it mean some other transport will
be tried?

I am asking because I want to backup the Cyrus server that handles the
lmtp requests, and shutting it down would help ensure that the disk
files are in a consistent state. When exim discovers there is no lmtp
server to talk to, I want it to hold messages and retry, rather than
failing the messages and bouncing them.

I used both index and search on "abort" in the info'ized manual, but
didn't turn up anything definitive. Neither did a search of the
archives.

I expect the behavior I want is the way exim operates, but I'd like to
be sure.

Thanks.
Ross Boylan