Hello, 

I am the system admin for a medium size company and i would like to apply staff signatures at an exchange level, mainly because it will keep everything uniform but i am having some issues with my Mac clients. I have created a transport rule in exchange, so that messages from me (just me for testing at the moment) when sent outside of the organisation applies disclaimer text, for the disclaimer text I have injected a HTML email signature, when I send an email from Outlook on my Windows 8.1 Professional virtual machine it reads fine both in Outlook, Mac OS X Mail and on iOS devices, when I try and send an email from Mac OS X Mail the disclaimer text is applied but in plain text and not HTML, this is a slight issue for me as when staff are sending out emails to clients there is a chance that the signature may not be formatted correctly.

Any guidance would be appreciated.

Thanks!

I ran into an issue similar not too long ago.  Take a look at this blog.

http://support.risualblogs.com/blog/2011/02/24/html-mails-sent-via-owa-and-outlook-2011-are-received-as-plain-text-mails-externally/

Hi Jack,

For your question, I want to ensure some points, please help collect answers for below questions:
1. How about OWA?
2. Whether all Mac OS X Mail client face this issue or just special one? Which message format are you set in problematic Mac OS X Mail account?
3. How about create signatures on Mac client and send message for testing?

Please ensure the setting in Mac client:
1. Go to the Mail menu and choose Preferences
2. Click on the Composing tab
3. Under Composing: check the setting in Message Format:
If it's Plain Text, please change it to Rich Text.

Thanks

Hello, 

Thank you for the reply, Using Outlook Web App on a Mac machine works fine, the signature is received and looks how it should.

I have tried sending mail from a different Mac client and the result is the same. 

Regarding creating the signatures in mac...do you mean create the HTML on mac and see if it works on the mac platform before adding it to the hub transport rule in exchange?

I have also made sure that the message type is of rich text format and still no luck.

Thanks in advance, 

Jack

Hi,

According to my research, this issue is caused by the setting on the ios devices. For your reference:
https://community.office365.com/en-us/f/158/t/187389

"The ios device send plain text and exchange won't reformat the mail to HTML and as such will screwup your HTML signature. The iPhone/iPad running 4 or later defaults to HTML unless you receive a plain text email. I've hunted around and there doesn't seem to be any settings to control this on ios."