bug#74395: 'mumi send-email' fails to detect created issue number

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hello,

I've been using 'mumi send-email', and one annoyance is that it doesn't
seem to reliably (or at all?) detect the created issue in the tracker,
even after the issue was synced to the MUMI database and visible through
the web interface.

For example, the issue https://issues.guix.gnu.org/74394 took about 3
minutes to be processed by GNU Debbugs and was available in the web
interface of Mumi, while the 'mumi send-email' client kept printing:

--8<---------------cut here---------------start------------->8---
Server has not yet received our email. Will retry in 60 seconds. 14 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 13 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 12 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 11 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 10 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 9 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 8 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 7 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 6 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 5 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 4 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 3 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 2 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 1 retries remaining.
Server has not yet received our email. Will retry in 60 seconds. 0 retries remaining.
Mail not acknowledged by issue tracker. Giving up.
--8<---------------cut here---------------end--------------->8---

It'd be nice to investigate and fix that.

-- 
Thanks,
Maxim