diff --git a/dmp-backend/web/src/main/java/eu/eudat/logic/managers/EmailConfirmationManager.java b/dmp-backend/web/src/main/java/eu/eudat/logic/managers/EmailConfirmationManager.java
index ed1b8e747..907ceac18 100644
--- a/dmp-backend/web/src/main/java/eu/eudat/logic/managers/EmailConfirmationManager.java
+++ b/dmp-backend/web/src/main/java/eu/eudat/logic/managers/EmailConfirmationManager.java
@@ -1,50 +1,90 @@
 package eu.eudat.logic.managers;
 
+import eu.eudat.data.entities.Credential;
 import eu.eudat.data.entities.LoginConfirmationEmail;
 import eu.eudat.data.entities.UserInfo;
+import eu.eudat.data.entities.UserToken;
 import eu.eudat.exceptions.emailconfirmation.HasConfirmedEmailException;
 import eu.eudat.exceptions.emailconfirmation.TokenExpiredException;
 import eu.eudat.logic.services.ApiContext;
+import eu.eudat.logic.services.operations.DatabaseRepository;
 import eu.eudat.models.data.security.Principal;
+import eu.eudat.queryable.QueryableList;
+import eu.eudat.queryable.jpa.predicates.OrderByPredicate;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;
 
 import java.util.Date;
+import java.util.List;
 import java.util.UUID;
 
 @Component
 public class EmailConfirmationManager {
 	private ApiContext apiContext;
+	private DatabaseRepository databaseRepository;
 
 	@Autowired
 	public EmailConfirmationManager(ApiContext apiContext) {
 		this.apiContext = apiContext;
+		this.databaseRepository = apiContext.getOperationsContext().getDatabaseRepository();
 	}
 
 	public void confirmEmail(String token) throws TokenExpiredException, HasConfirmedEmailException {
 		LoginConfirmationEmail loginConfirmationEmail = apiContext.getOperationsContext()
 				.getDatabaseRepository().getLoginConfirmationEmailDao().asQueryable()
 				.where((builder, root) -> builder.equal(root.get("token"), UUID.fromString(token))).getSingle();
+
 		if (loginConfirmationEmail.getExpiresAt().compareTo(new Date()) < 0)
 			throw new TokenExpiredException("Token has expired.");
-		UserInfo user = apiContext.getOperationsContext().getDatabaseRepository().getUserInfoDao().asQueryable()
+
+		UserInfo user = databaseRepository.getUserInfoDao().asQueryable()
 				.where((builder, root) -> builder.equal(root.get("id"), loginConfirmationEmail.getUserId())).getSingle();
+
 		if (user.getEmail() != null)
 			throw new HasConfirmedEmailException("User already has confirmed his Email.");
+
 		loginConfirmationEmail.setIsConfirmed(true);
+
+		// Checks if mail is used by another user. If it is, merges the new the old.
+		UserInfo oldUser = databaseRepository.getUserInfoDao().asQueryable().where((builder, root) -> builder.equal(root.get("email"), loginConfirmationEmail.getEmail())).getSingle();
+		if (oldUser != null) {
+			mergeNewUserToOld(user, oldUser);
+			expireUserToken(user);
+			databaseRepository.getLoginConfirmationEmailDao().createOrUpdate(loginConfirmationEmail);
+			return;
+		}
+
 		user.setEmail(loginConfirmationEmail.getEmail());
-		apiContext.getOperationsContext().getDatabaseRepository().getUserInfoDao().createOrUpdate(user);
-		apiContext.getOperationsContext().getDatabaseRepository().getLoginConfirmationEmailDao().createOrUpdate(loginConfirmationEmail);
+		databaseRepository.getUserInfoDao().createOrUpdate(user);
+		databaseRepository.getLoginConfirmationEmailDao().createOrUpdate(loginConfirmationEmail);
 	}
 
 	public void sendConfirmationEmail(String email, Principal principal) throws HasConfirmedEmailException {
 		UserInfo user = apiContext.getOperationsContext().getDatabaseRepository().getUserInfoDao().find(principal.getId());
 		if (user.getEmail() != null)
 			throw new HasConfirmedEmailException("User already has confirmed his Email.");
+
 		apiContext.getUtilitiesService().getConfirmationEmailService().createConfirmationEmail(
-				apiContext.getOperationsContext().getDatabaseRepository().getLoginConfirmationEmailDao(),
+				databaseRepository.getLoginConfirmationEmailDao(),
 				apiContext.getUtilitiesService().getMailService(),
 				email,
-				principal.getId());
+				principal.getId()
+		);
+	}
+
+	private void mergeNewUserToOld(UserInfo newUser, UserInfo oldUser) {
+		Credential credential = databaseRepository.getCredentialDao().asQueryable().where((builder, root) -> builder.equal(root.get("userInfo"), newUser)).getSingle();
+		credential.setUserInfo(oldUser);
+		databaseRepository.getCredentialDao().createOrUpdate(credential);
+	}
+
+	private void expireUserToken(UserInfo user) {
+		UserToken userToken = databaseRepository.getUserTokenDao().asQueryable()
+				.where((builder, root) -> builder.equal(root.get("user"), user))
+				.orderBy((builder, root) -> builder.desc(root.get("issuedAt")))
+				.take(1)
+				.getSingle();
+		userToken.setExpiresAt(new Date());
+		databaseRepository.getUserTokenDao().createOrUpdate(userToken);
 	}
 }