How To Make Dropdown Selection Email Subject?

The mail-tag corresponding to the form-tag of drop-down menu.

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Weird, I’d pasted that in a few times and it didn’t work, although it did now when I just checked. Thanks a lot. Would you mind taking a look at this one? It’s giving me the most trouble: https://www.ads-software.com/support/topic/your-message-was-sent-successfully-appearing-twice?replies=1#post-6032873

Thanks again for responding!