I'm using this filter to save emails I get using getmail to a local
maildir, and to forward them to an external gmail address using msmtp
My problem is that from time to time the server fails in forwarding them
with the following message:
550-Requested action not taken: mailbox unavailable
550 Failure sending mail. Try again later
I'm not sure why is this happening, but I usually see this when several
emails go out in a short period.
I suspect either the SMTP server or the recipient gmail account might be
temporarily blacklisting me.
So, I was thinking in introducing a short delay after or before sending
the email to msmtp, though I'm not sure how to do it.