Error "5.7.0 number of mime parts exceed"

I keep getting this error message everytime we try to send an email…

Error “5.7.0 number of mime parts exceed maximum  permitted”

Any ideas?

Thanks for your help

The error is related to a mail server’s antispam/antivirus settings. Do you get this message with all emails you send or just some email?

Hello Andrea,
what mail account does this happen on? I’d suggest contacting you mail provider, since this seems like a server-side issue, as IsoQuantic above suggests.