MimeWriter and smtplib: long list of 'To:' recipients

[Gillou]

Hi,

My application sends mail to a list of 'To' recipients but there are
problems when the list is long.
I have no access to the Postfix error log so I dunno what's the problem. All
recipients addresses are OK.
I use the MimeWriter like this:

fullmail = StringIO()
mw = MimeWriter(fullmail)
mw.addheader('To', 'jdoe at mailme.com, sombody at somewhere.com,
lotsofothers at lotsofdomains.com')
# Add other headers
...
mw.endheaders()
...

Is there something I missed ?

TIA for any hint.

--Gilles