[ZendTo] Problem with mail headers

[Nigel Kendrick]

One of our customers isn't getting dropoff notices and the mail.log shows:

Jan  6 14:16:34 asltux13 postfix/smtp[12616]: 1ADB7721101: to=<
customer at someaddress.mail <peter.fletcher at telent.com>>,
relay=smtp.xxxxxxx]:25, delay=13, delays=0.16/0.01/12/0.03, dsn=5.0.0,
status=bounced (host smtp.xxxxxx] said: 501 #5.1.3 Partial domain not
allowed: 'zendto' (in reply to MAIL FROM command))

I changed the 'myhostname' in Postfix's main.cfg and this has helped - but
now I see in the sent mail headers: Return-Path: www-data at ourdomain.co.uk

Having a quick search this may be down to the syntax used to generate the
email - would this be in some php (or other) code somewhere and any advice
on where to look and what to change. I'm rnning version 4.06

Thanks

Nigel Kendrick
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