I need your help, as I am stumped!

Recently when testing my emails, using one of the other services (sorry Litmus), I noticed that Apple Products (Apple Mail, iPhones, and iPads), Thunderbird, and Android 4.4.4 were rendering the Times New Roman font I coded, for headline type text, into a san serif font. Here is a sample of the code I'm using:

<tr valign="top">
    <td width=600 align="center" bgcolor="#fffefe" valign="top" style="text-align:center; vertical-align:top; font-family:'Times New Roman', Times, serif;font-size:21px;color:#e41937; mso-line-height-rule: exactly; line-height:24px;">
            <font face="'Times New Roman', Times, serif;" style="text-align:center;vertical-align:top; font-size:21px;color:#e41937; mso-line-height-rule: exactly; line-height:24px;">
            <strong>Thank you</strong>

I have also tried using "'Times New Roman', Times, serif !important" and "TimesNewRoman, 'Times New Roman', Times, serif" in the <td> and <font face=""> without any success.

After much time spent searching the web, as surely I'm not the first to encounter this issue, and coming up empty handed I'm asking the Community to offer me so education.

I am fairly new to the email world but not real green.

Thanks for your help!