There are two problems:
a. If you have connected to the Outlook data using the "Select from Outlook
Contacts" option in the Mail Merge Wizard, the Job Title is not available in
the list of fields (which is a subset of the fields available in Outlook).
b. ADDRESSBLOCK does not have a Job Title option
The simplest way to solve (a) is to initiate the merge from Outlook by
selecting a contacts folder then using Tools|Mail merge. This makes (almost)
all the fields in Outlook contacts available.
As for (b), if you look at the configuration options in the Insert Address
Block dialog you will not see a "job title" option anywhere. If you happened
not to need one of the other elements of the address (e.g. the company
name), you could use the Match fields dialog to insert the Job title where
the company name should appear, but typically if you want the Job Title
you're also going to want the company name.
Other possible workarounds are:
a. view the ADDRESSBLOCK field code using Alt-F9 and to insert e.g. {
MERGEFIELD Job_Title } inside the text that says
<<_COMPANY_
so you have
<<{ MERGEFIELD Job_title }
_COMPANY_
where the {} are the special field code braces you can insert using ctrl-F9
However, editing ADDRESSBLOCK code is not recommended. If you do it, test
carefully, and ensure that you never edit the Address block properties
because non-standard stuff is always discarded. Or save the block you need
as an Autotext or something so it's easy to re-insert.
b. Dont use ADDRESSBLOCK. Use the "individual fields" approach where each
element
of the address is inserted as an individual { MERGEFIELD } field and { IF }
fields are used
to deal with e.g. missing lines and other "trim".