Asynchronous Mail Posting with the MailDropHost Product

If the mail posting is arranged by the Zope product MailDropHost, Zope writes the mails of its Spooler (therefore Zope/ZMS answers with a "sent"); but the actual posting is done asynchronously; This is primarily relevant for great volumes since breaks and repetitions in the Mail-Queue may occur.
The installation of the product is sufficiently described in the delivered readme.txt. For the running operation the following hints are helpful; in case of problems proceed as follows (Linux):

1. Check existing spool files:
/opt/zope/lib/python/Products/MaildropHost/maildrop/spool/#

2. Two reasons for that: the sending slows down or the mails have defective addresses; the latter would be the case if a Zope manager (having no eMail-address attribute) is working as an editor and he receives a reject alert. Helpful may be a look in these spool files

3. Stop the spoolers
/opt/zope/lib/python/Products/MaildropHost/maildrop/ #
  ./stop_maildrop

4. Start the spooler in a background job with
/opt/zope/lib/python/Products/MaildropHost/maildrop/ #
nohup ./start_maildrop &