Does Zoho Support use DKIM for outgoing email?

Does Zoho Support use DKIM for outgoing email?

We are using Zoho Support to help our customers. The responses go out via email, sent by Zoho's mail servers, on behalf of our support address (e.g. support@mydomain.com). (We don't use Zoho Mail)

Does Zoho Support use DKIM ( http://en.wikipedia.org/wiki/DomainKeys_Identified_Mail) for these outgoing responses? If you do, great. If not, I fear that many of these messages to my customers (who are on gmail and yahoo for example) may end up in Spam. Since the messages are sent by Zoho, but purported to be from mydomain.com, gmail and yahoo may consider them spammy.

I see DKIM and SPF mentioned in the Zoho Campaigns help pages, but I haven't found them mentioned in Zoho Support.

1) Please let me know if you are using DKIM?

2) If we were to implement SPF as an additional measure, what host(s) should we add to our SPF DNS records?

thanks -Ricardo