Multi Domains Plugin

I have the ultimate branding plugin activated on my multisite and which customizes the welcome-email for new sites created. (This is the second email a user receives after receiving the first email to activate a new site)

I presume that the UB plugin alters the following two functions in Wordpress to achieve this:

update_welcome_subject
wpmu_welcome_notification

Now as soon as I activate the Multi-Domains plugin, the welcome-email now defaults back to the standard Wordpress email (ie "Wordpress" appears in the subject-line again, and the last line of the email reads: "--The Team @" and leaves off the platform name)

If I deactivate the Multi-Domains plugin again, a customized welcome-email is again sent out. Hence to re-summarize:

Multi-domain plugin activated = standard Wordpress welcome-email

Multi-domain plugin deactivated = custom welcome-email created by Ultimate Branding plugin

NB: I am not referring to the sent from field and sender email-address - those fields are working fine

I have also deactivated and reactivated all other plugins to see whether a different result could be obtained.

I have also not deleted any plugins which could leave data in a database-table.

I am also using a dedicated-ip, and I do not have domain-mapping activated.

I do have multi-db installed as well.

Please respond if you know how to solve this issue.